Araneidae - With Web and With Scent

The St. Andrew's Cross (Argiope keyserlingi). Photo by Louise Docker.

The orb-weavers are undoubtedly the best-known of all spiders. Ask anyone to imagine a spider and they will probably picture an orb-weaver (they may also have transcribed the words "some pig" in the web). This is something of an unfair characterisation - of the more than 100 recognised families of spiders, less than ten are orb-weavers. Still, it is one of the orb-weaving genera that holds the name of "spider", Araneus, which, as the only generic name used in Clerck's (1757) Aranei Svecici, the only taxonomic work recognised by the ICZN that predates the 1758 tenth edition of Linnaeus' Systema Naturae, is officially the oldest generic name in zoological nomenclature*. That's right - spiders came before humans. Nyeh nyeh nyeh.

*Admittedly Clerck did use the name Araneus for all spiders, not just species included in the modern Araneus.

The Araneidae are the largest family of orb-weaving spiders, with a little less than 3000 described species. They are actually a lot more numerous than you might realise - many species build their webs only at night, taking them down in the morning before hiding during the day and rebuilding the web every evening. The family is decidedly diverse in appearance - from the gaudy colours and spines of the Christmas spiders to the idiosyncratic figures of the tailed spiders to one group whose common name describes their appearance perfectly - the bird-dropping spiders.



The classic orb-web is made by first floating a line of sticky silk horizontally across a space between two anhoring points (such as a pair of branches), then running a second looser non-sticky strand along the initial strand. The spider then drops herself* from the centre-point of the second strand, trailing a third strand behind her, so that the second and third strands form a Y-shape. The vertex of the Y will be the centre of the web. The spider next constructs an outer frame, as shown above in a diagram by Ed Nieuwenhuys (the page linked to has diagrams of each of the stages in orb-web construction), then runs a series of spokes from the centre of the web to the outside. She then runs a broad spiral of non-sticky thread from the centre of the web until she reaches the outer edge. After that, it travels back to the centre laying a much tighter spiral of sticky thread, removing the non-sticky scaffold as she goes. As the sticky thread is stretched, the sticky coating breaks into a series of globules of coiled thread, which is how the web is able to be so elastic and stand up to the thrashings of captured prey. The spider herself is able to move about without being trapped by means of secretions produced by glands near the mouth with which she coats her legs. Forster & Forster (1999) refer to an experiment where the tips of a spider's legs were dipped in solvent before the spider was returned to its web. The spider initially showed great difficulty in moving due to the removal of its protective coating, though it was able to renew the covering and regain mobility. After the web has been completed, the spider will take up residence at the central hub, legs resting on the radiating spokes in order to feel for any vibrations. Araneid eyesight is almost non-existent, and orb-weavers are incapable of hunting without a web. They are perhaps the closest thing to a terrestrial filter-feeder, filtering the air for small animals.

*All spiders are referred to as female unless proven otherwise, like ships and birds of prey. It's another one of those things that make the English language so damn confusing.


An unidentified member of the genus Gasteracantha. These spiders come in a dazzling array of colours and ornamentations, and unlike many other araneids are often visible during the day, earning them such names as "jewel spider" or "Christmas spider". Colour patterns can vary significantly even between members of the same species. Photo from here.

Many araneids may vary the basic orb-web design further. Ladder-web spiders, for instance, have a long narrow web instead of the usual circle. The function of these is not really understood, though it has been suggested as a specialisation for catching moths - moths have a covering of loose scales on their wings which would normally allow them to shake off a web and escape, but it is suggested that the elongate shape of a ladder-web means that as the moth shakes off its scales, it falls onto a lower part of the web until eventually it is no longer able to escape. Many orb-weavers construct a stabilimentum, a zig-zag ladder-shaped structure that extends upwards from the central hub. Again, despite being such a distinctive structure, the function of the stabilimentum remains largely unknown, though subject to intense debate - suggested roles include strengthening the web (the original source of the name), disguising the position of the spider from predators or making the spider look bigger, attracting prey or even making the web more visible for larger animals and so reducing the risk of them walking or flying through it. One large and striking araneid found here in Australia, the St. Andrew's cross (Argiope keyserlingi), shown at the top of this post, gets its name because it builds four stabilimenta radiating from the central hub, while the spider itself sits with the front two and rear two pairs of legs held alongside each other, so the spider itself forms the eponymous cross shape.

Perhaps the most remarkable thing about araneids, however, is that despite the total dependence of most species on their webs for survival, some species no longer make them. The aforementioned bird-dropping spider (Celaenia) is so-called because its lumpy brown-and-white-splotched abdomen really does look like a lump of bird poo, offering excellent camouflage from discerning predators. Instead of constructing a full web, Celaenia simply hang from a leaf or a thread with their legs outstreched. There they catch and feed on moths (excellent pictures of hunting Celaenia can be seen at Esperance Blog). It used to be a mystery how this seemingly limited and haphazard means of capture could possibly feed the spider (after all, how many moths could reasonably be expected to pass by one point over the course of a night) until it was observed that a surprising proportion of the moths being caught (that is, all of them) were males, and that, far from passing by the spider accidentally, male moths will actually approach the spider and remain close by it until caught. It seems that the spider actually emits pheromones that mimic those of a female moth, luring their prey in with the false promise of sexual gratification (like a Trojan virus attached to a spam e-mail). The bolas spiders of the tribe Mastophoreae have refined this process further - as well as producing attractive pheromones, they also dangle a single sticky thread below themselves. When a moth approaches close enough, the spider spins the sticky thread around in the air until it sticks to the moth and they are able to draw it in. How bird-dropping and bolas spiders make their living until they become large enough to handle moths seems a little confused - Brunet (1996) claims that Celaenia construct standard orb-webs until they reach maturity, while bolas spiders produce different pheromones for attracting different-sized moths when at different ages. Forster & Forster (1999) and Yeargan (1994), in contrast, both claim that Celaenia spiderlings produce pheromones to attract psychodid midges. Interestingly, while bird-dropping and bolas spiders are both members of the subfamily Araneinae, it is debatable whether they are each other's closest relatives within the subfamily (Yeargan, 1994), so it is possible that their amazing pheromone-capture techniques could have arisen separately of each other!

REFERENCES

Brunet, B. 1996. Spiderwatch: A Guide to Australian Spiders. Reed New Holland: Sydney.

Forster, R. R., L. M. Forster. 1999. Spiders of New Zealand and their Worldwide Kin. University of Otago Press: Dunedin (New Zealand), and Otago Museum: Dunedin.

Yeargan, K. V. 1994. Biology of bolas spiders. Annual Review of Entomology 39: 81-99.

Back to the Scleritome - Tommotiids Revealed!

Disarticulated mitral sclerites of Micrina xiaotanensis. Image from GeoScience World.

Back in January, I brought you Scleritome Week where I looked at a range of fossil organisms that were originally described from bits of disassociated external skeleton. Some of these were still of unknown live appearance, some had turned out once soft-body fossils were discovered to look very different from what anyone had imagined. One such group that I didn't cover (though I did refer to them in passing) was tommotiids. Tommotiids are part of the Cambrian assemblage of scleritome animals that may or may not be related to each other, and may or may not include basal lophotrochozoans (the clade that includes brachiopods, annelids and molluscs). Tommotiids in particular have been suggested to be related to brachiopods, with which they share a similar shell ultrastructure (Holmer et al., 2002). Until recently, no articulated tommotiid specimens had been found, but comparisons of tommotiid sclerites with those of Halkieria and Wiwaxia had led to suggested reconstructions of tommotiids as bilateral armoured slug-like animals. A new paper by Holmer et al. (in press, 2008) suggests a quite different image.

An articulated tommotiid scleritome was recently described by Skovsted et al. (2008), though frustratingly I don't have access to the paper. Far from the imagined bilateral slug, sclerites of the tommotiid Eccentrotheca were joined into an expanding tube-shaped structure. Skovsted et al. inferred that Eccentrotheca was a sessile, vermiform (worm-shaped) filter-feeder. Such an interpretation, they argued, fit well with the potential brachiozoan (brachiopod + phoronid) affinities of tommotiids, though Eccentrotheca may have been more similar in appearance to the worm-like phoronids rather than the brachiopods.

The reconstruction of Holmer et al. (2008) focuses on another tommotiid, Micrina, which is the most brachiopod-like of the tommotiids. Micrina possessed two types of sclerite, the smaller and flatter sellate and the larger, cap-shaped mitral. By comparison with Halkieria, Williams & Holmer (2002) suggested that the two sclerites could have been situated at either end of a slug-shaped animal. However, the revelation from Eccentrotheca that at least some tommotiids might be sessile suggested that this reconstruction should be re-examined.



The new reconstruction of Micrina from Holmer et al. (2008) is shown above in a figure from that paper. Rather than being a slug-like animal, Micrina is reconstructed as a sessile filter-feeder like Eccentrotheca. However, Micrina differs from Eccentrotheca in being cup-shaped rather than vermiform. What it does bear a distinct resemblance to is a basal brachiopod similar to the diagram I used in an earlier post, which are also sessile filter feeders attached to a substrate by a short pedicle. In contrast to brachiopods, the two valves of Micrina would not have been able to form a sealed chamber, but the shell ultrastructure of Micrina does suggest the presence of a fringe of setae that Holmer et al. suggest could have served a protective function. One potential issue with the reconstruction is that mitral valves are generally preserved in much greater numbers than sellate valves when the reconstruction suggests they should be equally abundant, but this may be a preservation artefact resulting from the smaller and lighter construction of the sellate valve.

A sessile reconstruction for tommotiids has interesting implications for the interpretation of other Cambrian scleritome animals. Halkieria was suggested as a stem-brachiopod by Conway Morris & Peel (1995), but this was debated by Vinther & Nielsen (2005) who interpreted Halkieria as closer to molluscs. While the sessile reconstruction of tommotiids does not entirely rule out a halkieriid ancestry for brachiozoans (one could still potentially argue that halkieriids were ancestral to a tommotiid + brachiozoan clade), it does make it significantly less likely. Conway Morris & Peel (1995) suggested that the two large subterminal sclerites at each end of Halkieria could have been brought into apposition to form the two valves of the brachiopod shell, but the sessile tommotiids suggest that the equal-sized valves of brachiopods could have been derived from an unequally-valved ancestor.

They are also interesting by way of analogy with the chancelloriids, those incredibly confusing Cambrian animals whose sclerite structure demands they be lophotrochozoans, but whose sessile habit and radial organisation screams non-bilaterian. While there is no reason to suggest an actual phylogenetic connection between tommotiids and chancelloriids, the presence of a sessile habit in the former, which are almost undeniably lophotrochozoans, suggests that the radial nature of the latter may not be so difficult to resolve with a lophotrochozoan ancestry after all.

REFERENCES

Conway Morris, S., & J. S. Peel. 1995. Articulated halkieriids from the lower Cambrian of North Greenland and their role in early protostome evolution. Philosophical Transactions of the Royal Society of London Series B – Biological Sciences 447: 305-358.

Holmer, L. E., C. B. Skovsted, G. A. Brock, J. L. Valentine & J. R. Paterson (in press, 2008) The Early Cambrian tommotiid Micrina, a sessile bivalved stem group brachiopod. Biology Letters.

Holmer, L. E., C. B. Skovsted & A. Williams. 2002. A stem group brachiopod from the Lower Cambrian: Support for a Micrina (halkieriid) ancestry. Palaeontology 45 (5): 875-882.

Skovsted, C. B., G. A. Brock, J. R. Paterson, L. E. Holmer & G. E. Budd. 2008. The scleritome of Eccentrotheca from the Lower Cambrian of South Australia: lophophorate affinities and implications for tommotiid phylogeny. Geology 36 (2): 171-174.

Vinther, J., & C. Nielsen. 2005. The Early Cambrian Halkieria is a mollusc. Zoologica Scripta 34: 81-89.

Williams, A., & L. E. Holmer. 2002. Shell structure and inferred growth, functions and affinities of the sclerites of the problematic Micrina. Palaeontology 45 (5): 845-873.

Bird Evolution - Problems with Science

Hackett, S. J., R. T. Kimball, S. Reddy, R. C. K. Bowie, E. L. Braun, M. J. Braun, J. L. Chojnowski, W. A. Cox, K.-L. Han, J. Harshman, C. J. Huddleston, B. D. Marks, K. J. Miglia, W. S. Moore, F. H. Sheldon, D. W. Steadman, C. C. Witt & T. Yuri. 2008. A phylogenomic study of birds reveals their evolutionary history. Science 320: 1763-1768.

I'm afraid I'm going to be descending into cattiness for a moment later. I apologise in advance for any unwarranted snarkiness.

A paper (citation above) has appeared in today's edition of Science that adds to the ongoing debate on bird phylogeny. It is a fairly significant paper, giving the results of the largest molecular phylogenetic analysis to date for birds. As such, it largely supersedes the previous front-runner, the analysis of Ericson et al. (2006). However, most of the results of Hackett et al. (2008) are largely congruent with those from Ericson et al. (2006). So I'm a little bemused to read Chuck Hagner commenting that "What wasn’t expected was an apparent sister relationship between Passeriformes and Psittaciformes" and expressing surprise that Falconidae should cluster with that clade instead of with Accipitridae, when both these results had been reported in the 2006 paper. What is significant is that both these studies, conducted independently (no shared authors), found such similar results. Both studies (and the earlier Fain & Houde, 2004) found the same six major clades - Palaeognathae (ratites and tinamous), Galloanserae (gamebirds and waterfowl), Metaves (I'll explain in a minute), the "higher water-birds and allies" clade (including 'Ciconiiformes' and 'Pelecaniformes' intermixed), Charadriiformes and the "higher land-birds" (Passeriformes, Piciformes, Coraciiformes and allies).


Bird phylogeny as recovered by Hackett et al. (2008).

Metaves is one of the most controversial groupings of birds to have been proposed in recent years. It first made an appearance in a 2004 paper by Fain and Houde published in the journal Evolution. These authors coined the name Metaves for a clade containing nightjars, swifts and hummingbirds, pigeons and doves, sunbitterns, the kagu, mesites, tropicbirds and the hoatzin that was well-supported in an analysis of the β-fibrinogen gene. This clade was then completely unexpected - perviously, its members had been scattered among an assortment of other bird orders, and the only thing a number of them had previously had in common was that they had always looked a little out of place. In a message forwarded to the DML shortly after the publication of the 2004 paper, Peter Houde commented that the results had been so heterodox that it had been very difficult to get them published. The Charadriiformes, higher land-birds and higher water-birds together formed a clade that Fain and Houde dubbed "Coronaves". The Fain and Houde analysis did resolve the Charadriiformes and higher water-birds, but support was not great.

Ericson et al. (2006) increased the number of genes analysed to five, and again found the Metaves-Coronaves division of Fain & Houde (2004). They were also better able to resolve relationships within the major clades. However, the support for Metaves was completely reliant on the inclusion of the β-fibrinogen gene. If this gene was left out of the analysis, the clade collapsed.

Not too long after Ericson et al. (2006), a counter-sally from the morphological fort appeared in the form of the long-awaited Livezey & Zusi (2007) analysis. Using an awe-inspiring 2954 characters over 150 taxa, this morphological über-analysis bravely fought off the molecular novelties and called stridently for a return to more traditional relationships.

It is into this clash between the molecular data of Ericson et al. (2006) and the morphological data of Livezey & Zusi (2007) that Hackett et al. (2008) make their entrance. Hackett et al. increase the number of analysed genes to 19, and once again recover the much-maligned Metaves. Once again, though, the presence of this clade is dependent solely on the β-fibrinogen gene. The hoatzin abandons the Metaves and attaches itself to the base of the higher water-bird clade. I'm inclined to describe this as unsurprisingly surprising - once again, Opisthocomus is just being a prick. There seems to be a visible trail of respectability here - four years ago, Metaves had to fight its way for recognition in a respectable journal. With the publication of a paper supporting it in Science, it seems to have become a respectable hypothesis.

And that, really, is the source of my irritation. Nature and Science are widely regarded as the ultimate science journals, but it's difficult to escape the observation that many papers that appear in the two are, well, kind of crap. This is not the fault of the contributing authors, but results from the severe space restrictions on articles in these journals. At five very densely-written pages, Hackett et al. is a fairly long paper for Science, but the reader is left frustrated by the need to know about stuff that the authors were evidently forced to leave out. What happens when the analysis parameters change? If a given clade is collapsed, how does this affect the rest of the tree? Some of this is alluded to in the article, but there simply isn't the time for it to be explored properly. And was it lack of space that caused the authors to write clangers such as "flighted tinamous arose within the flightless Struthioniformes", which sounds to be suggesting that tinamous evolved or regained flight independently of other birds, rather than the far more likely scenario that flight was lost multiple times within the ratites? Nature and Science papers have been referred to as "extended abstracts" Sometimes, no matter how extended, an abstract just doesn't substitute for a paper.

Don't get me wrong, this is a very significant paper, and one that will provide a base-line for many future studies. It doesn't completely overthrow previous studies, but in the end that is exactly what is so fantastic about it - not that the results are completely unexpected, but that as more and more data is added, we can say more and more about the picture that has been developing over the past few years.

REFERENCES

Ericson, P. G. P., C. L. Anderson, T. Britton, A. Elzanowski, U. S. Johansson, M. Källersjö, J. I. Ohlson, T. J. Parsons, D. Zuccon & G. Mayr. 2006. Diversification of Neoaves: integration of molecular sequence data and fossils. Biology Letters 2 (4): 543-547.

Fain, M. G., & P. Houde. 2004. Parallel radiations in the primary clades of birds. Evolution 58 (11): 2558-2573.

Livezey, B. C., & R. L. Zusi. 2007. Higher-order phylogeny of modern birds (Theropoda, Aves: Neornithes) based on comparative anatomy. II. Analysis and discussion. Zoological Journal of the Linnean Society 149 (1): 1-95.

Ceratopsids: A Cretaceous Flash in the Pan

Leptoceratops, one of the latest-surviving ceratopsians. Reconstruction from here.

After the previous post on ceratopsians, Zach Miller asked if I could follow up my basal-ceratopsian-focused post with one on the more famous ceratopsids, which for various reasons, most significantly time, I had rather neglected.

Sorry, Zach - this is not that post.

But what I thought I would elaborate on was something I referred to offhand in that post about the significance of the basal ceratopsians compared to the ceratopsids proper. I mentioned that the small bipedal ceratopsians, despite their relative obscurity, actually persisted in North America for just as long as the giant ceratopsids, and were with them 'til the end. I would like to add to this that as surprising as it may sound to any readers who are only familiar with popular presentations of evolution and their tragic tendency to fall into the "March of Evolution" trap, this actually wasn't much of an achievement. For even though ceratopsids are one of the iconic dinosaur groups, instantly recognisable by 95% of the developed world's population, they weren't actually around for very long.

Most of you will have probably heard of the Triassic, Jurassic and Cretaceous periods that together make up the Mesozoic era of earth's history. While these periods are quite sufficient for broad generalisations about the history of life, palaeontologists generally find that they need finer-scale divisions to refer to more specific time periods. I recommend going to Palaeos.com if you want to see the subdivisions for the Jurassic and Cretaceous, because I'm going to have to refer to a few of them in the course of this post. I know I'll be checking back there regularly as I write this post, because personally I can never keep track of them all.


Yinlong downsi, the earliest known ceratopsian. Reconstruction by Andrey Atuchin.

I mentioned in the previous post that the earliest ceratopsians are known from the Late Jurassic. Specifically, Yinlong downsi comes from the Oxfordian, which started about 161 mya (million years ago). (Taxon ages for this post have been taken from Justin Tweet's Thescelosaurus! website.) In the rough grade system I used in the previous post, Yinlong would be a psittacosaur-grade ceratopsian*, but phylogenetically speaking it is the sister taxon to later ceratopsians. The earliest and most basal known protoceratopoid-grade ceratopsian, Liaoceratops yanzigouensis, comes from early in the Cretaceous, some time between the Valanginian (starting about 140 mya) and the early Barremian (130 mya). The earliest known Ceratopsidae, in contrast, didn't crash the party until the mid-Campanian (perhaps about 78 mya). Ceratopsians had been around for about 80 million years already by the time the ceratopsids appeared. Or to put it another way, less time separates us from the latest ceratopsids than separates the ceratopsids from the earliest ceratopsians! With their extinction at the end of the Cretaceous, about 65 million years ago, the Ceratopsidae are only known to have been around for about 15 million years - an impressively long time by human standards, but really not so very impressive when compared to the nearly 100 million years of ceratopsian history, or the more than 180 million years the Mesozoic lasted for in total.

*You may be wondering how the psittacosaur-grade ceratopsians fared in terms of longevity. Psittacosaurus is the latest well-established psittacosaur, and seems to have survived until about the end of the Early Cretaceous, about 100 mya. However, the analysis of Butler et al. (2008) suggests, albeit with rather low support, that the poorly-known (yet ambitiously-named) Micropachycephalosaurus hongtuyanensis might be a very basal ceratopsian. Despite this basal position, Micropachycephalosaurus actually dates from the Maastrichtian, the very last part of the Cretaceous. If Micropachycephalosaurus is indeed a ceratopsian (a proposition that should be taken very cautiously), then psittacosaur-grade ceratopsians survived at least relictually for almost the entirety of ceratopsian history.

True, the ceratopsids did attempt to cover up for lost time through rapid speciation, so that more ceratopsid taxa have been described from that last fifteen million years than all the non-ceratopsid ceratopsians over 100 million years, but this is like the rapid propagation of any fad - the flashy new designs may temporarily overshadow the old classics in the public eye, but the classics are still very much there.

REFERENCES

Butler, R. J., P. Upchurch & D. B. Norman. 2008. The phylogeny of the ornithischian dinosaurs. Journal of Systematic Palaeontology 6 (1): 1-40.

Big Horned Lizards

The ceratopsid Einiosaurus. Reconstruction from here.

Sometimes it's nice to write a post on something everyone's heard of, and I'm pretty sure almost everyone will have heard of this week's highlight taxon - the Ceratopsia. In one of my earliest posts on the Catalogue of Organisms, I nominated Triceratops horridus as one of the greatest of dinosaurs, rivalled as it is only by Tyrannosaurus rex and Apatosaurus ajax as an icon of all things dinosaur. And before anyone (I'm looking at you, Mike) weighs in to complain about the title to this post, I know that dinosaurs aren't lizards, the title was chosen in a spirit of tongue-poking and ribbing.

Ceratopsia is a very well-supported clade of dinosaurs. Not least of the characters uniting its members is the presence of the rostral bone - a small toothless bone at the tip of the upper jaw that is unknown from any other dinosaur and demonstrates the presence of a beak in the ceratopsians. Some sources have pointed out that the name Ceratopsia is actually mis-derived and argued for the name Ceratopia instead, as well as Ceratopidae and Protoceratopidae instead of the more commonly used Ceratopsidae and Protoceratopsidae, but in this case a long history of usage has won out over strict linguistic accuracy*. Most authors accept that ceratopsians form a clade called Marginocephalia with the Pachycephalosauria, but it is worth pointing out that while it is the best-supported hypothesis to date, the support for Marginocephalia is not overwhelming and the question is worth former investigation. While Sereno (1986) placed the Marginocephalia outside the ornithopods, a recent analysis by Butler et al. (2008) produced a phylogeny that nested Marginocephalia within a number of taxa that had been regarded in the past as ornithopods, suggesting that marginocephalians are derived from within the "hypsilophodontid" grade of dinosaurs. Interestingly enough, this is actually more congruent with older pre-cladistic theories of dinosaur relationships that had implicitly derived both ceratopsians and pachycephalosaurs from ornithopod ancestors. It also reduces the significant ghost lineage that Sereno's topology suggested for marginocephalians.

*Names ending in "-ops" have actually got a long history of being pains in the neck for zoological nomenclature. The ending "-ops" can be derived from the Greek word for "face", which is masculine, or for "appearance", which is feminine. Because many an author has ended a genus name in "-ops" without indicating which ending was intended, it is unclear for many such names whether they were meant to be masculine or feminine, a significant issue because it affects the form of any associated species names. It is because of this confusion that the ICZN has declared that all names ending in "-ops" are to be treated as masculine, regardless of derivation.


Reconstruction of Psittacosaurus by Pavel Riha.

The earliest known Ceratopsia date from the Late Jurassic. Ceratopsians can be divided into three distinct grades that have been classified as separate families in the past, but of which two are paraphyletic. These grades are the psittacosaurs, protoceratopoids and Ceratopsidae. The Ceratopsidae are the most familiar of the ceratopsians, and include the large horned quadrupedal forms. This group includes some of the first dinosaurs described from North America, albeit many from fragmentary remains which tragically means that such fantastic names as Agathaumus, Dysganus and (my personal favourite) Polyonax mortuarius, the "dead master of many", have been resigned to the oblivion of nomen dubium status. I'm going to leave the Ceratopsidae for some other time and introduce the more basal ceratopsians.

Psittacosaurs are the basalmost group of ceratopsians - small and at least facultatively bipedal, they look not too different from a basal ornithopod and were classified as such when first described (Osborn, 1924), though a connection between psittacosaurs and ceratopsians was also recognised quite early on (though again, in those pre-Hennigian days the separation of psittacosaurs from ceratopsians as part of a paraphyletic Ornithopoda was not really seen as a problem). The majority of psittacosaurs have been included in the genus Psittacosaurus - in fact, with over ten described species (though not all of these may be valid), Psittacosaurus provides a welcome exception to the tendency of dinosaur systematists to keep their genera as small as possible (while sixteen species have been referred to Triceratops, almost all of these are invalid - Ostrom & Wellnhofer, 1990). In recent years, a few other "psittacosaur-grade" genera have been described, such as Chaoyangsaurus and Yinlong. The frill formed by the extension of the bones of the back of the skull that is so characteristic of other ceratopsians is absent from psittacosaurs, though a slight rearward curve of the squamosal (as well as the short snout) does help give the skull of Psittacosaurus a distinctly boxy appearance. Psittacosaurus is actually one of the best-known of all dinosaurs, with literally hundreds of known specimens of all different ages. One specimen is known that preserves a row of long tubular bristles running down the tail of unknown function, probably display*.

*With the admission that "display" is all too often something of a cop-out explanation for unusual structures.


Mounted skeleton of Archaeoceratops oshimai, one of the basalmost protoceratopoids. Photo from here.

I'm using the name "protoceratopoids" (a term plucked more or less out of thin air) to refer to the taxa previously included in the Protoceratopsidae, a taxon now well established to be paraphyletic with regards to the Ceratopsidae (the two groups together forming the Neoceratopsia). Taxonomic concepts in this grade are currently a little unstable - there may be a more restricted Protoceratopsidae formed from taxa forming a monophyletic group with Protoceratops, while other protoceratopoids are parcelled off into families such as Leptoceratopsidae. In protoceratopoids we see the development of the frill characteristic of Neoceratopsia, albeit still fairly small in many species. Most protoceratopoids lack the horns of ceratopsids, and were also much smaller than the ceratopsids. Some protoceratopoids such as Leptoceratops (which if the run of available reconstructions is to be believed existed for no other purpose than to provide food for larger, meaner-looking reptiles) probably remained bipedal, but other lines became larger, heavier and eventually quadrupedal. Analyses differ as to how many times quadrupedality evolved in ceratopsians (You & Dodson, 2004). One very basal protoceratopoid, Archaeoceratops oshimai, was a very gracile impish-looking little form that actually looks better adapted as a runner than does Psittacosaurus. Though often dismissed as basal forms, the bipedal ceratopsians were to survive for just as long as the quadrupedal forms, and Leptoceratops was actually a contemporary of Triceratops, one of the latest Ceratopsidae.

Mention should also be made of the role of Protoceratops as an accessory to one of the biggest frame-jobs in the history of palaeontology. The first known specimen of the theropod Oviraptor was discovered overlying a nest of eggs that were identified as belonging to Protoceratops. It was this that gave Oviraptor its name ("egg thief"), and for many years Oviraptor was reconstructed mercilessly plundering protoceratopsid nests. It wasn't until fairly recently that it was discovered that the "Protoceratops" eggs didn't belong to that taxon at all, but were in fact Oviraptor eggs, and far from stealing them, the much-maligned Oviraptor had probably been a diligent mother incubating them! I did attempt to speak to Protoceratops about its role in this shameful affair, but it refused to comment on grounds of being extinct.

The majority of known basal ceratopsians - all psittacosaurs and most protoceratopoids - come from Asia, particularly northern Asia, and this is universally accepted to be the place of origin of this clade. The Ceratopsidae, in contrast, is only known from North America, as is the sister taxon to Ceratopsidae, Zuniceratops. It appears likely that their ancestors dispersed to North America from Asia before giving rise to the Ceratopsidae. Again, how many times this dispersal occurred is uncertain - members of the Leptoceratopsidae were also found in North America. The analysis of Xu et al. (2002) placed Leptoceratopsidae in a very basal position distant from Ceratopsidae, while that of You & Dodson (2004) found them as sister taxa (though I should point out that the latter analysis included significantly fewer taxa than the former). Two records of Ceratopsia from outside Laurasia are rather problematic. The South American Notoceratops, based on a single jawbone, was originally described as a ceratopsian but is suspected to have been a hadrosaur - unfortunately, this question will probably never be fully resolved because the type specimen has gone AWOL. The Australian Serendipaceratops is supposed to be very similar to Leptoceratops, but is known only from a single ulna.

REFERENCES

Butler, R. J., P. Upchurch & D. B. Norman. 2008. The phylogeny of the ornithischian dinosaurs. Journal of Systematic Palaeontology 6 (1): 1-40.

Osborn, H. F. 1924. Psittacosaurus and Protiguanodon: two Lower Cretaceous iguanodonts from Mongolia. American Museum Novitates 127: 1-16.

Ostrom, J. H., & P. Wellnhofer. 1990. Triceratops: an example of flawed systematics. In Dinosaur Systematics: Approaches and Perspectives (K. Carpenter & P. J. Currie, eds.) pp. 245-254. Cambridge University Press.

Sereno, P. C. 1986. Phylogeny of the bird-hipped dinosaurs (Order Ornithischia). National Geographic Research 2: 234–256.

Xu, X., P. J. Makovicky, X.-L. Wang, M. A. Norell & H.-L. You. 2002. A ceratopsian dinosaur from China and the early evolution of Ceratopsia. Nature 416: 314-317.

You H. & P. Dodson. 2004. Basal Ceratopsia. In The Dinosauria, 2nd ed. (D. B. Weishampel, P. Dodson & H. Osmólska, eds.) pp. 478-493. University of California Press.

Support Your Local Taxonomy

The Tsushima leopard cat (Prionailurus bengalensis euptilurus). Photo from Nature Conservation in Japan.

Those of you who have read Antoine de Saint Exupéry's book The Little Prince may recall a scene near the beginning of the book describing the discovery of B612, the asteroid the Prince lives on. The asteroid is first observed by a Turkish astronomer, who travels to a European academy to present his discovery. Arriving in his traditional Turkish garb, he is ignored by the European academics and returns home unrecognised. A year later, the same Turkish astronomer returns to the same academy and presents the exact same data, but this time wearing a European suit and tie. This time, he is applauded for his remarkable discovery.

The ideal of science is that, as scientists, we should be completely objective in our judgements, and not allow our personal biases to affect us. In reality, of course, those personal biases can be very difficult to avoid. National pride and other such factors often have a stronger hold on us than we may realise. Taxonomy is a branch of science in which a certain degree of subjectivity is all but unavoidable, and personal biases can often affect whether or not a given author will accept the validity of a given taxon. The best-known example of this lies in the conflict that supposedly exists between "splitters" and "lumpers" - those who would tend to emphasise the differences between taxa and those who would tend to emphasise their similarities. In reality, of course, a given author may be both a splitter and a lumper depending on circumstances.

All that connects only tangentially with my subject in this post, but it may go some way to explaining how my subject came about in the first place. On my bookshelf at home I have a copy of Iwahashi's (1992) Reddo Deeta Animarusu ("Red Data Animals"), a guide to Japanese endangered animals (both vertebrates and insects). In the mammal section are listed a number of species that I have not seen listed in non-Japanese sources, and I've always wondered what exactly they were. While I have often flicked through the book and admired the many wonderful photos in it, my Japanese abilities (which are just about extensive enough to let me read Dr. Slump and Doraemon) are not sufficient for me to follow the text. Today, I decided to see if I could find out what these species may be.

Cervus pulchellus Imaizumi, 1970: Tsushima-jika ("Tsushima deer"). Tsushima is a island about midway between Japan and the southern end of Korea. I've not been there, though I have seen it from the ferry between the two countries. If the deer found on Tsushima represent a separate species, then a publication date as recent as 1970 would make it one of the most recently described large mammals, especially in as densely populated a region as Japan. As it turns out, prior to 1970 the Tsushima deer were regarded as belonging to the Honshu (the main island of Japan) subspecies of sika deer Cervus nippon centralis, before Imaizumi distinguished them as a separate species on the basis of features such as a narrow constriction of the jugal bone of the skull, a deep emargination of the nasal bone, and a longer first antler segment. Molecular studies cluster Tsushima sika among other Japanese sika (Nagata et al., 1999). However, they also find a distinct divide between northern and southern sika, which Groves (2005) formally recognised as two separate species - Cervus nippon for the southern sika (including C. pulchellus as a distinct subspecies) and C. yesoensis for the northern sika (including C. centralis). Most interestingly, deer assigned to C. nippon centralis from southwesternmost Honshu were found by Nagata et al. (1999) to also not belong to that taxon, but instead clustered with the Tsushima sika. According to Groves (2005), the dividing line between the two species is west of Biwa-ko, the large lake on Honshu.

Felis euptilura Elliot, 1871: Tsushima-yama-neko ("Tsushima mountain cat"). Despite the name, and unlike the deer, this taxon is not restricted to Tsushima - it is also found in Korea and Far Eastern Russia. It appears that most authors would include this taxon as a subspecies in Prionailurus bengalensis (or Felis bengalensis), the leopard cat of eastern Asia, and recognition of euptilura as a separate species is restricted to Japanese and Russian sources. However, molecular analysis of leopard cat populations by Tamada et al. (2008) did find a clear distinction between northern populations (Tsushima, Korea, Siberia, China and Taiwan) and southeast Asian populations. If these genetic differences indicate a specific distinction, Prionailurus euptilurus may yet be a valid species.

Sus riukiuanus Kuroda, 1924: Ryuukyuu-inoshishi ("Ryukyu boar"). In most places, this small boar from the Ryukyu Islands becomes a subspecies of Sus scrofa, the Eurasian wild boar. Mind you, as pointed out by Groves (2007), "Sus scrofa" as generally recognised covers a wide range of variation and a number of quite distinct subspecies, and the potential that it should be divided into more than one species should be considered. One interesting detail - genetic analysis indicates that the Ryukyu boar is not closely related to Sus scrofa leucomystax, the boar of the Japanese mainland, and the two subspecies represent separate colonisations from the Asian mainland (Watanobe et al., 1999).


A somewhat gaunt-looking reconstruction of Canis hodophilax, taken from here. Though the site says that the artist responsible for this reconstruction is unknown, it bears a distinct resemblance to the mount shown on this page.

Canis hodophilax Temminck, 1839: Nihon-ookami ("Japanese wolf"). Actually, I'd heard of this one before I acquired the Iwahashi book. Canis hodophilax (sometimes spelt 'hodophylax', but as demonstrated by Harper, 1940, the spelling with an 'i' is correct) is the wolf of Honshu that is, regrettably, now extinct (officially around 1905, though it may have survived until later) as a result of the introduction of rabies and habitat alteration (Knight, 1997). Hokkaido, the northern island of Japan, was home to a distinct wolf taxon, Canis lupus hattai, also now extinct. Opinions differ about whether C. hodophilax was a distinct species or a subspecies of Canis lupus, but whatever its ranking it was certainly a distinctive animal. Canis hodophilax was the smallest known wolf taxon. Most sources attribute this to island dwarfism, but I'm personally a little suspicious that Honshu is small enough to cause significant dwarfism, and I wonder to what degree its mountainous habitat was a factor in its small size. In contrast to the poor opinion wolves have been held in elsewhere in the world, the shama-inu seems to have been regarded quite favourably by most Japanese. Wolves controlled numbers of deer or boar that might have otherwise damaged crops. Unfortunately, rabies was introduced to Japan in the late seventeenth century. Even more significant was probably the abandonment of mountain villages for the lowlands as the population of Japan increased and the country became more intensively agronomised (or whatever the word is), resulting in the loss of previous areas of high prey animal populations. As an aside, the specific name of the Honshu wolf translates as "trail-watcher", and may refer to a Japanese tradition of a wolf appearing near a traveller on the road at night. In a somewhat Orphean manner, turning to look at the wolf would cause it to attack, but if the traveller let it be then the wolf would protect them until they reached their home, at which point it would simply disappear back into the woods.

REFERENCES

Groves, C. 2005. The genus Cervus in eastern Eurasia. European Journal of Wildlife Research 52: 14-22.

Groves, C. 2007. Current views on taxonomy and zoogeography of the genus Sus. In Pigs and Humans: 10,000 years of interaction (U. Albarella, K. Dobney, A. Ervynck & P. Rowley-Conwy, eds.) pp. 15-29. Oxford University Press.

Harper, F. 1940. The nomenclature and type localities of certain Old World mammals. Journal of Mammalogy 21 (2): 191-203.

Iwahashi, J. (ed.). 1992. Reddo Deeta Animarusu: a pictorial of Japanese fauna facing extinction. JICC: Tokyo.

Knight, J. 1997. On the extinction of the Japanese wolf. Asian Folklore Studies 56: 129-159.

Nagata, J., R. Masuda, H. B. Tamate, H. Hamasaki, K. Ochiai, M. Asada, S. Tatsuzawa, K. Suda, H. Tado & M. C. Yoshida. 1999. Two genetically distinct lineages of the sika deer, Cervus nippon, in Japanese islands: comparison of mitochondrial D-loop region sequences. Molecular Phylogenetics and Evolution 13 (3): 511-519.

Tamada, T., B. Siriaroonrat, V. Subramaniam, M. Hamachi, L.-K. Lin, T. Oshida, W. Rerkamnuaychoke & R. Masuda. 2008. Molecular diversity and phylogeography of the Asian leopard cat, Felis bengalensis, inferred from mitochondrial and Y-chromosomal DNA sequences. Zoological Science 25 (2): 154-163.

Watanobe, T., N. Okumura, N. Ishiguro, M. Nakano, A. Matsui, M. Sahara& M. Komatsu. 1999. Genetic relationship and distribution of the Japanese wild boar (Sus scrofa leucomystax) and Ryukyu wild boar (Sus scrofa riukiuanus) analysed by mitochondrial DNA. Molecular Ecology 8 (9): 1509-1512.

Three-Quarters of a Century, and We Still Care about a Dead Horse

Phar Lap at the Flemington race track in 1930. Photo from Wikipedia.

Overheard on the news yesterday evening - 76 years after he died in 1932, forensic investigations have fairly conclusively demonstrated that Phar Lap died of arsenic poisoning. The presence of elevated levels of arsenic in hair taken from the mane of Phar Lap's mounted hide was first reported back in 2006 but as the exact procedure that had been used to preserve his skin was unknown, it was uncertain whether the arsenic had been in his system before death or whether it had been added as part of the preservation process. Comparison with other preserved animals has allowed researchers from South Australia and Victoria to distinguish between pre-mortem and post-mortem doses of arsenic, and revealed that Phar Lap had ingested a large dose of arsenic in the last 30 to 40 hours before his death.

For those of you who are not from Australasia and may be wondering who exactly Phar Lap was, Phar Lap was a racehorse born in Timaru in New Zealand in 1926. He was bought by a Sydney trainer and taken over to Australia - though the colt appeared in such poor health on arrival that the invester who had ponied (hah hah) up the money for him refused to pay for his training and the trainer was forced to offer to train him for free, his only compensation being a share in any of the horse's winnings. Despite this unpromising start, Phar Lap ended becoming one of the most successful horses in Australia, winning 37 of the 51 races he was entered in, and becoming the only horse ever to start as the favourite to win in three successive Melbourne Cups (for the record, he came second in the first of these, won the second, and eighth in the third though he won every other race he was entered in that year). Such was the degree of Phar Lap's success that an assassination attempt was actually made against him in 1930. In 1932, Phar Lap was taken to America to race in the Agua Caliente Handicap, America's richest race. Despite the unfamiliar conditions and a hoof injury a few weeks before the race on March 20th, Phar Lap (dubbed the 'Red Terror' by the Americans) won by three lengths. In little more than a fortnight, he was dead.

Needless to say, many have regarded the sudden death of the celebrated racehorse with suspicion. An autopsy after his death was inconclusive. Many suspected that he had been poisoned by American interests, a rumour that has persisted ever since. Others have suggested that he died of a rapidly developing bacterial infection. It now seems clear that he did die of arsenic poisoning, but it should be immediately added that this does not prove foul play. Racehorses at the time were often given tonics containing ingredients that seem incredible today, such as arsenic or strychnine, and records show that Phar Lap was no exception. It has also been suggested that arsenic compounds used in treating nearby orchards against insects could have been blown onto the grass Phar Lap was pastured on. The horse's death could well have been accidental.

Meanwhile, Phar Lap became more confirmed as an Australian and New Zealand icon. Like many icons, the reverence accorded probably seems illogical to one not raised with it - after all, who would believe that the death of a horse 76 years ago would be regarded as news? Mind you, the winning of an American race by an Australasian horse was then a remarkable achievement, perhaps surpassed in significance only by the Australian team winning the America's Cup yachting tournament in 1983 and becoming the first non-American team to take the Cup since its inauguration 132 years previously. The position of Phar Lap in Australasian popular culture has also been reinforced by the nature of his history - foaled in New Zealand, rose to success in Australia - which has led to his becoming a focus of the trans-Tasman rivalry, like Crowded House and the pavlova, as both sides stake their claims. Indeed, perhaps no better symbol of this rivalry can be seen than the fate of Phar Lap's remains - while his hide is on display in Melbourne and his heart is in Canberra, his skeleton is one of the most popular exhibits at Te Papa Tongarewa in New Zealand.

Moustache Whales

The bowhead whale (Balaena mysticetus), the original paradigm of baleen whales, now unfortunately one of the most endangered whale species. Photo from here.

This week's Taxon of the Week post is the biggest yet. And while that is (as you shall see) an absolutely gods-awful pun, I just couldn't resist it, because my topic today is a group of animals that really can't be discussed without at least some reference to size - the Mysticeti.

Mysticeti are the baleen whales. The name can actually be translated as "moustache whales", which makes them sound like the Groucho Marxes of the whale world. Like Groucho Marx, that's not a real moustache. Unlike Groucho, it's not painted on with greasepaint. The baleen of baleen whales is an array of bristle-edged plates coming down from the outer margins of the palate and which the whales use to filter food out of the water. Baleen whales are usually referred to as plankton feeders, but different species are actually specialised towards different foods. The smaller rorquals, for instance, tend to prefer fish, while Dale Rice apparently examined two sei whales (Balaenoptera borealis) (out of a catch of 39) at a whaling station in California in 1959 that had only rudimentary, non-functional baleen and yet appeared to be in perfectly good health with stomachs full of anchovies (Watson, 1981). Darren Naish wrote a series of posts some time ago on one group of baleen whales, the rorquals, that you can read here.



Whales are such seemingly familiar animals, which species listed in so many popular books, that it may come as a surprise to some that the taxonomy of whales is actually a rather shaky affair, as exemplified by the description of Balaenoptera omurai as recently as 2003 (Wada et al., 2003). Minke (Balaenoptera acutorostrata), blue (Balaenoptera musculus), Bryde's (Balaenoptera edeni) and great right (Balaena glacialis) whales are all representative "species" that are split or lumped to varying degrees from author to author. The sheer size of baleen whales and their marine habitat makes comparison of specimens a logistically daunting affair (see the photo above by Nick Pyenson, via Matt Wedel, of a blue whale jaw, with skull propped up against the wall in the background), and such specimens few and far between. After all, it's not as if a full-grown sei whale (let alone blue whale) can be popped into a vial of ethanol for preservation, while any sort of dissection is liable to require a forklift or crane, a stepladder, and a chainsaw. A large portion of the taxonomic research on whales has been based on strandings, but these carry their own potential sources for error. For instance, colour pattern or body conformation may become altered or distorted post mortem, and more than one cetacean has been inadvertently restored as an animated corpse.


Reconstruction of the Oligocene toothed mysticete Janjucetus hunderi, one of the most basal known mysticetes. Image from here.

The fossil record of mysticetes dates back to Late Eocene, where they are represented by Llanocetus denticrenatus (Steeman, 2007). Not too surprisingly, these early mysticetes retain teeth. In another incarnation of the ghastly Great Chain of Being metaphor that has haunted popular presentations of evolution and sadly refuses to die*, the toothed mysticetes are often implied to been nothing more than steps on the path to the modern baleen whales. In fact, the Late Oligocene played host to both early representatives of the clade Chaeomysticeti, the toothless baleen whales, as well as a number of toothed mysticetes, including Janjucetus hunderi and the Aetiocetidae. Seeing as Llanocetus is more closely related to the Chaeomysticeti than the latter two taxa, the lines leading to these taxa must have been in existence since at least the Eocene.

* Which brings up the question - is it possible to be truly haunted by something before the haunter is dead?

Outside the crown clade of modern mysticetes, but within the Chaeomysticeti, were the Late Oligocene Eomysticetoidea. Eomysticetus whitmorei is known from a large portion of a skeleton from South Carolina (Sanders & Barnes, 2002). With a skull about one and a half metres long, E. whitmorei wouldn't have been a spectacularly large whale, perhaps comparable in size to a modern minke. The really interesting thing about Eomysticetus is that it retains a number of primitive features not found in modern baleen whales. One of the significant features of the cetacean skull has been the process of telescoping, where the lower part of the skull has been extended forward while the top part has receded back, resulting in modern cetaceans having the nostril(s) (the blowhole) positioned more or less (depending on taxon) directly above the eyes. The archaeocetes, the paraphyletic stem group to modern cetaceans, largely lack this feature, though the beginnings of it can be seen in more derived forms. In Eomysticetus, the opening of the nostrils would have been positioned about a third of the way down the rostrum, far closer to the front of the skull than any modern mysticete. Between Eomysticetus and early fossil odontocetes, the indications are that while the process of telescoping began in the archaeocetes, it was actually brought to culmination independently in the mysticetes and odontocetes. What is more, Eomysticetus also possessed a less telescoped skull than the toothed Aetiocetidae, suggesting that the Aetiocetidae represent a third lineage to have converged on the telescoping trend - and adding to the point that the toothed mysticetes were not evolutionary no-showers even after the appearance of the baleen whales!

REFERENCES

Sanders, A. E., & L. G. Barnes. 2002. Paleontology of the Late Oligocene Ashley and Chandler Bridge Formations of South Carolina, 3: Eomysticetidae, a new family of primitive mysticetes (Mammalia: Cetacea). Smithsonian Contributions to Paleobiology 93: 313-356.

Steeman, M. E. 2007. Cladistic analysis and a revised classification of fossil and recent mysticetes. Zoological Journal of the Linnean Society 150: 875-894.

Wada, S., M. Oishi & T. K. Yamada. 2003. A newly discovered species of living baleen whale. Nature 426: 278-281.

Watson, L. 1981. Sea Guide to Whales of the World. Hutchinson: London.

The Hawaiian Superducks

The turtle-jawed moa-nalo, Chelychelynechen quassus, largest of this group of birds. Image by Stanton Fink.

The always impressive Darren Naish put up a post a couple of days ago on recent publications about phorusrhacoids, the giant carnivorous birds that once stalked South America (and only a gigantic carnivorous bird can truly be said to "stalk"), including (among other things) the recent claim that one supposed phorusrhacoid, Brontornis, was not a phorusrhacoid at all but a relative of the Anseriformes. In the course of the comment thread on that post, mention has been made of the moa-nalo, and I thought I'd put up an explanatory post for anyone not familiar with the latter.

Moa-nalo were large (up to 7.6 kg - Ziegler, 2002), flightless goose-like birds that were once found in the Hawaiian Islands, but seem to have not long survived the arrival of hungry humans. To date, four species have been described from various islands (Olson & James, 1991) - Chelychelynechen quassus from Kauai*, Thambetochen xanion from Oahu, T. chauliodous from lowland Maui and Molokai, and Ptaiochen pau from highland Maui. Moa-nalo are not yet known from the main island of Hawaii, which was home to two species of Branta goose (Paxinos et al., 2002), including the (just) surviving nene (B. sandvicensis). Branta geese were also found on the other Hawaiian islands. Wetmore (1943) described a fossil anserid species from Hawaii, Geochen rhuax, that he regarded as distinct from Branta (and very like the Australian Cereopsis), but the fragmentary remains this species was described from are not really sufficient to tell whether it is a goose or moa-nalo (or something else again)**. The unnamed 'giant Hawaiian goose' of Olson & James (1991) is quite definitely a Branta (Paxinos et al., 2002).

*Wryly amusing quote of the day comes from the etymology of the species name for this taxon (Olson & James, 1991): "Latin, quassus , broken, shattered, in reference to the regrettably fragmented condition of the type material, which was probably deposited as a complete skeleton but was unfortunately exposed in a jeep trail."

**Olson & James (1991) again, referring to the discovery of the Geochen material underneath an old lava flow: "From their very friable and warped appearance, the bones were almost certainly heated until glowing, with all organic material in the bone having been combusted."

Perhaps most interesting about the moa-nalo is their phylogenetic relationships (isn't it always?). Despite their goose-like appearance, Olson & James (1991) suggested on the basis of their ossified syringeal bullae that moa-nalo were actually more closely related to the dabbling ducks of the genus Anas (two species of which are also found on Hawaii), and possibly even derived from the common mallard (A. platyrhynchos). This view was corroborated to some extent by ancient DNA analysis (Sorenson et al., 1999) which, while it found the moa-nalo as the sister group to Anas rather than within it, definitely indicated a duck rather than goose ancestry for them. The moa-nalo therefore seem to have undergone a rapid and significant change in morphology as they adapted to flightless herbivory. The Molokai population of Thambetochen chauliodous seems to have actually gone so far as to lose the furcula!

REFERENCES

Olson, S. L., & H. F. James. 1991. Descriptions of thirty-two new species of birds from the Hawaiian Islands: part I. Non-Passeriformes. Ornithological Monographs 45: 1-88.

Paxinos, E. E., H. F. James, S. L. Olson, M. D. Sorenson, J. Jackson & R. C. Fleischer. 2002. mtDNA from fossils reveals a radiation of Hawaiian geese recently derived from the Canada goose (Branta canadensis). Proceedings of the National Academy of Sciences of the USA 99: 1399-1404.

Sorenson, M. D., A. Cooper, E. E. Paxinos, T. W. Quinn, H. F. James, S. L. Olson & R. C. Fleischer. 1999. Relationships of the extinct moa-nalos, flightless Hawaiian waterfowl, based on ancient DNA. Proceedings of the Royal Society of London Series B – Biological Sciences 266: 2187-2193.

Wetmore, A. 1943. An extinct goose from the island of Hawaii. Condor 45 (4): 146-148.

Ziegler, A. C. 2002. Hawaiian Natural History, Ecology, and Evolution. University of Hawaii Press.

Clutching Crinoids

The Lower Carboniferous Parisocrinus labyrinthicus. The inclusion of Parisocrinus in Euspirocrinidae is uncertain - it was excluded by Eckert and Brett (2001), but included by Waters et al. (2003). Photo from The Virtual Fossil Museum.

This happens to be the third Taxon of the Week post on crinoids. In the earlier posts (see here and here), I mentioned the basic divisions within crinoids and some details of structure, so I'm just going to take those as read for this post.

The specific topic of this post is the cladid family Euspirocrinidae. I could start by saying that the Euspirocrinidae were found from the late Silurian to the early Carboniferous, but to be honest I already be fudging issues. As explained in the second of the posts linked to above, the Cladida have been the most successful of the three major crinoid clades. However, relationships within the Cladida are subject to a great deal of uncertainty. While a detailed subdivision between suborders, superfamilies and families was recognised in the Treatise on Invertebrate Paleontology by Moore et al. (1978), its apparent authority was largely an illusion. Apart from the two clades that have been recognised in the past as separate subclasses (the Flexibilia and Articulata), very few of the various cladid "families", "suborders", etc. that have been recognised are well-defined. The situation was bad enough that Kammer and Ausich (1996) apparently felt the need to abandon all attempts at subdividing the Cladida and simply listed all genera alphabetically, recognising at most a purely pragmatic division between primitive and advanced grades. As such, it is suspected that many of the cladid "families" represent polyphyletic groupings, and the Euspirocrinidae is one such grouping.

Such as it was, the Treatise Euspirocrinidae comprised crinoids with cone- or bowl-shaped cups, five large oral plates, slender isotomously-branching (i.e. branching into two equal parts) arms and stout round stems. A brief revision of the group by Eckert & Brett (2001) removed some of the more distinct taxa and added a few more defining features, most notably restricting the family to taxa with a large, non-porous anal sac. For sessile filter-feeders like most crinoids, excretion is often a serious matter, especially if you live in a low-energy environment. If indigestable wastes are released too close to the mouth, the poor animal could end up re-ingesting its own wastes. Many crinoids solved this problem by developing sizeable anal sacs or tubes that carried wastes a reasonable distance from the calyx before releasing them. The unusual stout, relatively inflexible columns of the Euspirocrinidae could indicate that they lived in habitats with relatively low currents (Breimer, 1978), as such a column provides extra support but would be prone to breakage in higher-energy environments. Euspirocrinids would have fed by passive capture of small food particles settling from above.

The type genus of the Euspirocrinidae, Euspirocrinus, is a particularly noteworthy genus. Uniquely among Silurian cladids, Euspirocrinus developed the ability to tightly coil its arms. Eckert & Brett (2001) suggest that rather than being a passive capturer of food particles like other euspirocrinids, Euspirocrinus was probably an active grabber and trapper of larger food items, such as small animals. The tightly coiled arms formed a chamber above the mouth in which prey could be captured, broken down and digested. A similar feeding style has been suggested for the living Holopodidae.

REFERENCES

Breimer, A. 1978. Autecology. In Treatise on Invertebrate Paleontology pt. T. Echinodermata 2. Crinoidea (R. C. Moore & C. Teichert, eds.) vol. 1 pp. T331-T343. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

Eckert, J. D., & C. E. Brett. 2001. Early Silurian (Llandovery) crinoids from the Lower Clinton Group, western New York State. Bulletins of American Paleontology 360: 1-88.

Kammer, T. W., & W. I. Ausich. 1996. Primitive cladid crinoids from Upper Osagean-Lower Meramecian (Mississippian) rocks of east-central United States. Journal of Paleontology 70: 835-866.

Moore, R. C., N. G. Lane, H. L. Strimple, J. Sprinkle & R. O. Fay. 1978. Inadunata. In Treatise on Invertebrate Paleontology pt. T. Echinodermata 2. Crinoidea (R. C. Moore & C. Teichert, eds.) vol. 2 pp. T520-T759. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

Linnaeus' Legacy #8

Linnaeus' Legacy part Eight is up at When Pigs Fly Returns. This month's keywords: handsome devil, toucan, Douglas Adams, horrible mutated ants, Rhenocystis, Aetogate, flying trilobite, ornithopod bias, marine monsters.

Gnah! Gagrella! Headdesk!

'Gagrella' splendens - is this the face of Evil? Photo by sswroom.

Please permit me to vent some frustration. I've written before about the ghastly legacy left to many areas of harvestman taxonomy by the work in the first half of the 1900s of Carl-Friedrich Roewer, henceforth referred to as the Antichrist of Arachnology, through his use of artificial classification systems and slipshod taxonomy. In the past, I personally have managed to remain relatively unscathed by the dark influence of Roewer, who did not deal much with the Australian opilionidan fauna. In the last few days, this has sadly changed dramatically. I have found myself wandering into the toxic wasteland that is Gagrella.

The Gagrellinae are a sizable subfamily found in tropical and subtropical Asia and the Americas. The centre of diversity for the subfamily is in Asia, whence about 700 species have been described. Many of these species are exceedingly colourful, strikingly ornamented and just downright remarkable. The problem is that most of the Gagrellinae, including Gagrella itself, have not really been revised since Roewer's massive investigation of the group, culminating in a monograph of the Asian Gagrellinae published in four parts over 1954 and 1955. As with other groups of harvestmen, Roewer used an artificial classification system based on characters such as the numbers of nodules in the legs or spines on the carapace - characters which have sometimes since been shown to not even be consistent between members of the same species, let alone the same genus (there are specimens of other taxa that, if one was to use Roewer's identification system, the left side of the animal would key out as one genus while the right side would key out as another). It is therefore quite likely that, were a full revision to be conducted, many species would have to be placed in different genera from their current position. With, as I said, about 700 species involved, this would be a mammoth task.

And yet there is a second layer of ghastliness, to make the problem even more difficult. Of the species assigned to Gagrellinae, a little less than 200 have been assigned to the largest genus, Gagrella. The type species of this genus is one Gagrella signata. However, when Roewer worked on the genus, he moved G. signata out of Gagrella and into another genus, Crassicippus, leaving the remaining species as Gagrella. Because the genus name is required to always stay with the type species, this actually meant that what Roewer called Crassicippus should have been called Gagrella, while what he called Gagrella should have been something else! Unfortunately, almost all authors following Roewer used his inaccurate sense of Gagrella, meaning that of those nearly 200 species, none of them actually belong to Gagrella unless they happen by coincidence to have been placed in the wrong genus and are actually closer to G. signata.


Unidentified South American Gagrellinae, congregating suspiciously. Photo by Bruno Buzatto.

Under strict application of the rules of nomenclature, what is now 'Gagrella' should actually be called Hexomma, that being the oldest genus name synonymised with Gagrella sensu Roewer in the past (Crawford, 1992). Unfortunately, the name Hexomma has been used as a valid genus in all of about three publications since it was first published back in 1876. Also, there are serious doubts about whether the type species, Hexomma vulcanicum, is actually identifiable - Roewer (1954), who may or may not have seen the type specimens*, claimed it to be based on unidentifiable juveniles, and the type specimen(s) seems to have since gone AWOL (Crawford, 1992).

*Roewer (1954) claims to have examined type specimens that he had borrowed from Vienna, but then eight lines later lists "Holotypus (Thorell) (Mus. Stockholm, Genua?)". As the Vienna specimens were correctly attributed to Doleschall rather than the later Thorell (albeit from the wrong publication), the Vienna record seems more likely to be accurate. Thorell later redescribed Hexomma vulcanicum as Gagrella vulcanica, and the Stockholm/Genoa specimen listing probably refers to the specimen used by Thorell for the redescription (and so not actually a holotype).

Why does all this matter to me? I am currently trying to write a description of a new species of Gagrellinae. Seeing as I am not in a position to conduct the full revision of the Asian Gagrellinae, my best option for now would be to follow the Roewer classification, despite its faults. Unfortunately, the species keys out to 'Gagrella'... What am I (or other workers on Asian Gagrellinae) to do about this huge ugly pile of taxonomic blancmange? Among the options:

1. Move everything currently in Gagrella to Hexomma: Probably not that good an idea, considering that Hexomma is not a well-defined genus and many (if not most) of the species will end up having to be moved out anyway.


2. Conserve the definition of Gagrella as used by Roewer: One option might be ask the ICZN to conserve Roewer's usage of Gagrella. Under normal conditions, this would be ideal, but in this case much the same issues apply as with the first option - what's the point with conserving Gagrella in its current condition if most of the species are probably going to end up having to move anyway?


3. Run screaming in horror from the entire concept of Asian Gagrellinae and end up crouched into foetal position and whimpering in the darkest recesses of the wet collection: At the moment, this option is looking increasingly attractive...

REFERENCES

Crawford, R. L. 1992. Catalogue of the genera and type species of the harvestman superfamily Phalangioidea (Arachnida). Burke Museum Contributions in Anthropology and Natural History 8: 1-60.

Roewer, C. F. 1954. Indoaustralische Gagrellinae (Opiliones, Arachnidae). (Weitere Weberknechte XVIII). 1. Teil. Senckenbergiana Biologica 35 (3-4): 181-236.

Circus of the Spineless #33

The 33rd edition of Circus of the Spineless is up at Seeds Aside (ha ha! even the botanists cannot escape the lure of the squishy!mwa ha! mwa ha ha!) so head over there for more invertebrate fun than you can shake a pedipalp at!

Implications of Aetogate: Who Owns the Data?

I thought I'd say some more things about the Society of Vertebrate Paleontology's ethics committee's judgement about the Aetogate affair. A lot of ink has been spilled (or keypad buttons thumped, if that's the more appropriate phrase these days) over this - in addition to the links I supplied the other day, I'd recommend reading Darren Naish's and Chris Rowan's comments. Most of all, though, I would recommend Janet Stemwedel's posts on the subject. Many people have disagreed with the SVP's opinion that the public coverage of this affair has caused more harm than good, and I would add my voice to the disagreers. Whatever the result of the investigation, it has led to what I think can only be productive discussion about proper practice in palaeontology and, by extension, science in general. Without the impetus of public scrutiny, this investigation would have probably never happened.

The point that I would like to focus on, though, relates to the right to publish on museum material. One of the allegations investigated was that the Lucas et al. (2006) paper establishing a new genus Rioarribasuchus for the species previously known as Desmatosuchus chamaensis (material held at the New Mexico Museum of Natural History and Science - NMMNHS) was rushed into publication through an inadequate reviewing process in order to pre-empt a more detailed and more thoroughly reviewed paper by Parker (2007) that established a new genus Heliocanthus for the same species. In response to Parker's complaints, Lucas et al. counter-claimed that Parker did not have authority or permission to publish on the NMMNHS material, and "That the 'Desmatosuchus' chamaensis specimen belongs to the NMMNHS, and hence should by rights have been studied and named by NMMNHS staff" (quote from Darren Naish). To quote from the SVP decision:

For example, Parker claimed that he had permission from staff members of the New Mexico Museum of Natural History and Science to study the aetosaur material and publish on the fossils, but Lucas et al. assert that only Lucas can grant such permission, and that he did not. Parker claimed that Lucas said in a conversation at the museum (corroborated by a witness) that he (Parker) should name the new genus. However, neither Lucas nor his provided witness claim to have any recollection of this conversation. Parker noted that he expressed his intention to publish on the new genus in a number of venues (abstracts, talks, other papers), but Lucas et al. state that they were unaware of his intentions to publish a new name, noting that they knew only that Parker considered the genus assignment incorrect. They do cite Parker and Irmis (2005) in their 2006 paper as justification for the assignment of D. chamaensis to a new genus, but maintain that they came to their own determination, independent of the work by Parker and his colleagues.

The big question hanging over all this, in my opinion, is that of who has the say on publication in the first place. This has implications beyond palaeontology only, and relates to the status of museum collections of any kind. The implicit claim that NMMNHS material should only be worked on by NMMNHS staff is rather dubious. Any sizable museum will hold material of many more groups of organisms (or, for that matter, art genres or archaeological periods or whatever) than it has staff working on them. As a result, it is far from unusual for outside experts to work and publish on a museum's collection. Indeed, the professional relationships resulting from such outside input are regarded as a vital part of the scientific environment. Interloans of material are regularly made between research institutions. Having worked on material from another museum, what obligations does the outside investigator hold in regards to permission to publish?

The NMMNHS staff are claiming that Lucas required explicit permission to publish on the 'Desmatosuchus' chamaensis material. Speaking from a personal viewpoint, this is in total contradiction to my own experience. While admittedly it is up to the individual instute to establish their own conditions, the general expectation is that if a museum grants permission for research to be conducted using its specimens, it is also implicitly granting permission for the researcher to publish their findings. After all, publication of research is one of the most important factors in the progress of scientific knowledge, and research that cannot be published and communicated might has well have never been conducted in the first place. In order to check whether my personal expectations were actually correct, I dug up a couple of loan agreements relating to specimen collections in have on loan myself from other museums. While none commented explicitly on whether or not recipients on loans have the right to publish, one requested that:

If the work on the borrowed material is published, the borrower should either forward a reprint or indicate when and where his paper is to be published. [Emphasis in the original]

Another stated in more detail (name of institute removed by yours truly):

• Any published material that includes results based in total or in part on Museum specimens must include an acknowledgement of the Museum.


• The Museum would be grateful if the borrower could send to the relevant collection manager a copy of any paper published that cites AM specimens.

Both these sets of loan conditions only make sense if the right to publish is assumed, with the perfectly reasonable caveat that the museum in question be fully informed of any such publications. It is possible that the NMMNHS has different conditions that do require explicit permission to publish, but I would suggest that if so, then they are placing an unethically large barrier to scientific progress in general. Unfortunately, the SVP committee did not themselves make any explicit statements in their correct practice guidelines about the right to publish, though they did say that:

Visiting researchers should inform the museum of the results of their work based on the museum’s collections. Museums benefit in many ways from having researchers work on their collections. In some cases, the results of research can lead to news articles that will increase the profile of the museum in the local, national, or international community. In others cases, the information can be presented through exhibits and public programs. Thus the museum will want to know what visiting scientists have done with results of the observations on their specimens, and especially what abstracts or papers are published that include reference to material in their collections. Published papers, published abstracts, dissertations, and theses should be provided to the repository in a timely fashion.

Again, the right to publish once access to specimens has been granted seems to be fairly implicit. However, I am rather disappointed that it could not be made explicit. After all, as Chris Rowan stated, "Many of these suggestions seem to fall into the category of 'bleedingly obvious', but if this case hasn't made it crystal clear exactly why even the bleedingly obvious should be explicitly stated, I don't know what will". Many of the best practice guidelines recommended by the SVP, such as improved communication and the desirability of independent investigation of results, really only funtion meaningfully in the presence of the right to publish.