Stilts and Avocets

Visit a healthy wetland in many parts of the world and you may be able to see boldly patterned, lightly built birds with remarkably long legs and bills wading through the shallows. These are the members of the Recurvirostridae, commonly known as the stilts and avocets.

American avocets Recurvirostra americana, from here.

About a dozen species of recurvirostrid are currently recognised, depending on the exact classification scheme in play. They are divided between three genera with the avocets forming the genus Recurvirostra and the stilts divided between Himantopus and Cladorhynchus. The most obvious distinction between the two subgroups is in the shape of the bill: that of stilts is straight but avocets have a distinct upwards curve towards the end of theirs. A fourth genus has often been included in the Recurvirostridae for the ibisbill Ibidorhyncha struthersii, a striking-looking inhabitant of the upland rivers of the Himalayan plateau, but uncertainty about this bird's phylogenetic position has led most recent authors to exclude it from the family.

The recurvirostrids feed mostly on small aquatic invertebrates such as brine shrimp or insect larvae. Their long legs, among the longest relative to body size of any bird, allow them to wade in deeply in search of prey. Stilts actively probe the waters and underlying sediment whereas avocets tend to forage by sweeping their bill through the water side to side. Avocets and the banded stilt Cladorhynchus leucocephalus of Australia prefer brackish waters such as lagoons and estuaries, with the banded stilt congegrating around the great salt lakes of inland Australia. Breeding is conducted by monogamous pairs that share the duty of incubating their simple nest on the ground near water. These nests may be gathered into loose colonies; the banded stilt forms particularly large colonies in which the chicks are herded into communal creches of several hundred.

Pied stilt Himantopus leucocephalus, copyright JJ Harrison.

The majority of recurvirostrids are patterned with black or dark brown and white. The red-necked avocet Recurvirostra novaehollandiae has the head and neck coloured reddish-brown as does the American avocet R. americana during the breeding season. The banded stilt has a broad reddish-brown band across the top of the breast. There is also the black stilt Himantopus novaezelandiae of New Zealand, which is somewhat self-explanatory. Beaks are black in all species; the legs are grey in avocets and red in stilts.

Four geographically distinct species of avocet occupy the modern world: the American avocet in North America, the red-necked avocet in Australia, the pied avocet Recurvirostra avosetta in Eurasia and Africa, and the Andean avocet R. andina in South America. The Andean avocet is a bird of high altitudes, occupying shallow, alkaline lakes in the upper Andes. Cladorhynchus includes only the banded stilt. The most varied taxonomy concerns the genus Himantopus. Historically, all the black-and-white stilts (and sometimes also the black stilt) have been recognised as a single near-cosmopolitan species. In more recent years, the trend has been towards recognition of five or six distinct species in the genus. Most of these species are well separated geographically except for in New Zealand where the black stilt shares its range with the pied stilt Himantopus leucocephalus, a more recent immigrant from Australia. The breeding range of the black stilt is currently restricted to a relatively small area of New Zealand's South Island, and the species is considered endangered due to factors such as habitat alteration and the threat of hybridisation with the more abundant pied stilt*.

*It's worth spending some thought on the role of hybridisation as a conservation risk. Some observers may express concern that regarding hybridisation as a threat per se carries uncomfortable intonations of "racial purity", and that limiting the available gene pool may do more harm than good. After all, it's not as if the black stilt heritage of hybrid individuals is just gone (hybrids between the two species are, I believe, fully fertile and able to produce offspring of their own). The question is, I suppose, do the black stilt genes actually persist in the mixed population? Or does selection and/or drift winnow them out over time? This would be a difficult question to answer, and not without risk to find out.

Banded stilts Cladorhynchus leucocephalus and red-necked avocets Recurvirostra novaehollandiae, copyright Ed Dunens.

Phylogenetically, it is reasonably well established that recurvirostrids form a clade with the ibisbill and oystercatchers. This clade is in turn closely related to the plovers of the Charadriidae; indeed, many recent phylogenies have indicated that the recurvirostrid-oystercatcher clade may even be nested within the plovers as generally recognised. Considering the relatively small number of species in each clade, it might seem reasonable to suggest the recurvirostrids be reduced to a subfamily of the Charadriidae, but bird taxonomists being bird taxonomists, there seems to be more of a push to divide the Charadriidae up instead.

The fossil record of the Recurvirostridae is limited. A handful of species have been assigned to this family from the Eocene, but all are known from limited remains and their position is questionable. Coltonia recurvirostra is known from part of a wing from Utah; it was a relatively large bird, appearing to be more than one-and-a-half times the size of any living recurvirostrid. Fluviatilavis antunesi was described from a femur, humerus and radius from Portugal but was described as exhibiting some primitive features not found in modern recurvirostrids. It is also worth noting that its original description (Harrison 1983) compared it most favourably with the ibisbill, so if that species is not to be regarded as a recurvirostrid, probably neither is Fluviatilavis.

REFERENCE

Harrison, C. J. O. 1983. A new wader, Recurvirostridae (Charadriiformes), from the early Eocene of Portugal. Ciências da Terra 7: 9–16.

The Patagonian Land Penguin

Take a good look at the figure above, which comes from Mayr (2009). It shows the fossilised tarsometatarsus (the fused long bone of the foot) of a bird from the late Oligocene of Patagonia. This may be one of the single most mysterious specimens in the fossil record. It represents all we know to date of Cladornis pachypus, described by Argentinean palaeontologist Florentino Ameghino in 1895. The appearance of the bone, being very broad and flat relative to its length, is quite bizarre and does not much resemble the tarsometatarsus of any other known bird.

The first thing that should be pointed out is that, whatever it was, Cladornis was a large bird. The specimen is not completely preserved (part of the proximal end of the bone has been lost) but its overall shape suggests that its original length was probably not too much longer than what we have. As such, the tarsometatarsus was probably comparable in length to that of a large pelican. However, it was much wider relative to length than that of a pelican, suggesting the possibility of a more robust bird. The shape of the bone's end indicates that the toes would have been widely spaced, and it may have even approached a zygodactyl arrangement (with two toes pointed rearwards and two forwards, like a modern parrot*) (Mayr 2009).

*When explaining this to my partner, I suggested that he imagine a parrot the size of a pelican. He shuddered and declared that he would rather not.

When Ameghino (1895) first described Cladornis, he interpreted it as an aquatic bird and suggested a relationship to the penguins, albeit in an extinct family Cladornidae (later authors would correct this to Cladornithidae). Later, noticing that it was preserved in association with terrestrial mammals, he declared that it was not marine and was possibly even terrestrial (he also included another species from the same formation, Cruschedula revola, in the Cladornithidae; this species is based on part of a scapula and there is no telling if it was related to Cladornis or not). He still maintained its relationship to the penguins (Ameghino 1906). Ameghino had a bit of a thing for trying to find the origins of all major modern vertebrate groups in his native South America (one of his other works was a book arguing for an Argentinean origin of humans) and it is possible that this was in play here. Nevertheless, the idea of a 'Patagonian land penguin' held sway until Simpson's (1946) review of the fossil penguins, in which he declared that Cladornis was "so very unlike any other penguin, recent or fossil, that I can only consider its reference to that group as erroneous".

This left Cladornis' taxonomic position completely up in the air (the question of whether Cladornis itself could get up in the air is, of course, currently completely unswerable). Wetmore (1951) included Cladornis in the Pelecaniformes, because...reasons. The closest he gave to an explanation was, "The only suggestion that has come to me is that possibly they may belong in the order Pelecaniformes, in which I have placed the family tentatively in the suborder Odontopteryges, where it is located with two others of almost equally uncertain status. This allocation is wholly tentative and is no indication of belief in close relationship in the three diverse groups there assembled". He would later move Cladornis into its own suborder, Cladornithes, and no close relationship to the 'Odontopteryges' (now the Pelagornithidae) has been suggested since. Our current understanding of bird phylogeny finds Wetmore's remaining 'Pelecaniformes' to correspond to three or four independent clades (the Pelecanidae, Suliformes, Phaethontidae and probably Pelagornithidae) so his assignment of Cladornis to this group becomes almost completely uninformative.

Which is pretty much where we're forced to leave things. Mayr (2009) included Cladornis in his chapter on 'land birds', with other taxa discussed in this chapter belonging to the clade Telluraves. However, this was motivated more by a lack of any idea what to do with it otherwise than anything else (it is possible that Cladornis' sub-zygodactyly played a role, but not all zygodactylous birds belong to the Telluraves). I did notice a similarity in proportions between the Cladornis tarsometatarsus and the corresponding bone in the large phorusrhacid Brontornis, making me wonder if anyone had ever compared the two, but this may well be only superficial. Most recent authors have assumed that the Cladornis tarsometatarsus is simply too weird, too unique, for any resolution of its affinities to be reached without first finding more complete remains of the animal.

REFERENCES

Ameghino, F. 1895. Sur les oiseaux fossiles de Patagonie et la aune mammalogique des couches a Pyrotherium. Boletín del Instituto Geográfico Argentino 15 (11–12): 501–602.

Ameghino, F. 1906. Enumeración de los Impennes fósiles de Patagonia y de la Isla Seymour. Anales del Museo Nacional de Buenos Aires, serie 3, 6: 97–167.

Mayr, G. 2009. Paleogene Fossil Birds. Springer.

Simpson, G. G. 1946. Fossil penguins. Bulletin of the American Museum of Natural History 87 (1): 1–99.

Wetmore, A. 1951. A revised classification for the birds of the world. Smithsonian Miscellaneous Collections 117 (4): 1–22.

The Ostrich: From Whence this Derpy Horror?

Male and two female ostriches Struthio camelus, copyright Yathin S. Krishnappa.

Ostriches are widely known for two things: firstly, that they are the largest living bird by a quite respectable margin, and secondly, that they look ridiculous. Seriously, is there anyone out there who can look at the animals in the picture above and not think them ludicrous. Though I am, admittedly, invoking the luxury of distance: my uncle spent a year or two raising ostriches back during the brief boom of ostrich farming in New Zealand in the early 2000s, and I can say from experience that what looks humorous from afar is, close up, intimidating in a way no other animal is. They're just so tall*.

*Not to mention their well-earned reputation for gobbling down any item that attracts their attention. There are numerous stories out there demonstrating that wearing jewellery in an ostrich enclosure is a bad idea.

The modern ostrich is commonly regarded as a single species, Struthio camelus, found in savannah and semi-desert habits around Africa. There are some grounds for recognising the Somali ostrich S. molybdophanes of the Horn of Africa as a separate species—it is both genetically and morphologically divergent from other ostrich populations (for instance, its skin is blue rather than pink or red), and there is a small amount of overlap in range between Somali and typical ostriches—but this question remains open. Other subspecies are the North African ostrich S. c. camelus, the southern ostrich S. c. australis, and the Masai ostrich S. c. massaicus of Tanzania and Kenya. A fifth subspecies, the Arabian ostrich S. c. syriacus, became extinct around 1940, though it is worth noting that mitochondrial DNA extracted from specimens of Arabian ostriches in the British Museum did not separate them from the North African ostrich (Robinson & Matthee 1999). Ostriches can not really be confused with any other modern bird: not only is their remarkable size (matched by the remarkable size of their eggs), but they are the only birds to have reduced the number of toes to just two, with only the third and fourth toes of the standard bird foot remaining. This feature is generally presumed to be related to their cursorial lifestyle.

More evidence that ostriches are just daft. Copyright Georges Olioso.

Ostriches are members of the group of birds known as palaeognaths, that also includes such birds as the emu, kiwis, cassowaries, rheas and tinamous (the flightless members of the palaeognaths are commonly referred to as the ratites, but recent studies have cast doubt on whether flightlessness in the palaeognaths has a single origin). Phylogenetic relationships within the palaeognaths have been shuffled about considerably over the years (and even now are probably not really settled), but it is generally agreed that ostriches probably diverged from their nearest living relatives a long time ago (Burleigh et al. [2015], for instance, place them as the sister taxon to all other palaeognaths). Just how long ago we can't really say, the early fossil record of ostriches (and palaeognaths in general) being pretty dire. The heron-sized middle Eocene Palaeotis weigelti from Germany has been suggested to be a direct relative of ostriches but the evidence for this is equivocable (Mayr 2009). The earliest undoubted ostrich is the early Miocene Struthio coppensi from Namibia, and this is already similar enough to modern ostriches to be placed in the same genus.

Fossil ostriches are known from southeastern Europe to China, and survived across much of Asia until the Pleistocene. Several species have been named, but the usual vagaries of preservation make it debatable how many are distinct. Matters are complicated by several 'species', such as the Ukrainian Struthio chersonensis, that have been named based on fossil eggshells, raising questions as to whether such names can or should be applied to associated body fossils. Also unknown are the phylogenetic relationships between modern and fossil ostriches: whether the Eurasian ostriches represented a single or multiple dispersals out of Africa, or even whether ostriches may have originated in Eurasia*.

*It was suggested at one point that ostriches may have originally come from India, only dispersing to Africa after the subcontinent latched onto the rest of Eurasia. Support for this was based on the phylogenetic hypotheses that ostriches and the South American rheas formed an exclusive clade within the palaeognaths, and that the divergence of the flightless ratites was directly influenced by the division of the Gondwanan supercontinent (a South American-African connection being inconsistent with Africa being the first part of Gondwana to be separated). As support for both these arguments has declined, the need to somehow get ostriches out of Africa has evaporated.

The earliest known ostrich, the aforementioned Struthio coppensi, was a smaller and more slender bird than the modern ostrich, but some fossil species were larger. Perhaps the tallest ostrich species was S. oldowayi of the Tanzanian Pleistocene, which had a femur about a third as long again as the modern species. The femur of the Georgian Plio-Pleistocene S. dmanisiensis was not quite as long as that of S. oldowayi but it was considerably more robust, suggesting a proportionally solidly-built bird (Vekua 2013). Struthio brachydactylus (which sometimes moonlights as S. chersonensis) from the Miocene of Ukraine was also robustly built, albeit probably no taller (if not shorter) than a modern ostrich, but its main distinction lies in it taking the toe reduction seen in other ostriches even further. The fourth toe was reduced, with more weight placed on the third toe, making this species functionally almost single-toed (Boev & Spassov 2009).

REFERENCES

Boev, Z., & N. Spassov. 2009. First record of ostriches (Aves, Struthioniformes, Struthionidae) from the late Miocene of Bulgaria with taxonomic and zoogeographic discussion. Geodiversitas 31 (3): 493–507.

Burleigh, J. G., R. T. Kimball & E. L. Braun. 2015. Building the avian tree of life using a large-scale, sparse supermatrix. Molecular Phylogenetics and Evolution 84: 53–63.

Mayr, G. 2009. Paleogene Fossil Birds. Springer.

Robinson, T. J., & C. A. Matthee. 1999. Molecular genetic relationships of the extinct ostrich, Struthio camelus syriacus: consequences for ostrich introductions into Saudi Arabia. Animal Conservation 2: 165–171.

Vekua, A. 2013. Giant ostrich in Dmanisi fauna. Bulletin of the Georgian National Academy of Sciences 7 (2): 143–148.

Coscoroba

So what was the bird in Wednesday's photo? It didn't take long for it to be recognised for what it was, a coscoroba.

The coscoroba Coscoroba coscoroba, photographed by Christopher Valentine at the Jardin des Plantes, Paris. Photographing this animal was not entirely easy: it was in the process of preening, and every time that we tried to get a photo, its head would dive back into its feathers and we'd have yet another photo of a headless coscoroba.

The coscoroba (its name refers to the sound of its call) is a waterbird of coastward parts of southern South America, with its range having extended over the past century as far north as Uruguay (Kear 2005). In general appearance, it resembles a small swan (and is often called the 'coscoroba swan'). The most obvious difference between a swan and a coscoroba is that the latter lacks a bare patch of skin between its eyes and its beak. Coscorobas also have a flatter, more 'duck-like' beak than swans. Another significant difference can be seen in their behaviour: swans and geese are characterised by what is called a 'triumph ceremony', where a male approaches his partner (swans form life-long pair bonds), raising and lowering his head while calling, and is answered by her in kind. This behaviour is particularly common after the male has seen off a potential rival (hence the name), and probably serves to maintain the pair bond. Coscorobas, it seems, are far too refined for such brazen posturing, and limit themselves to a little quiet murmuring of their eponymous call (Johnsgard 1965).

Because of its 'not-quite-swannish' nature, the coscoroba has often been seen as a link between swans and some other group of waterfowl, such as geese or whistling ducks. Molecular studies (e.g. Donne-Goussé et al. 2002) have placed it as sister to the Cape Barren goose Cereopsis novaehollandiae of Australia, with the two together sister to the swans. This does seem a little counter-intuitive, as superficially Cereopsis does not appear very coscoroba-like, but it is relatively well-supported. The purported similarities between the coscoroba and whistling ducks, on the other hand, are quite possibly plesiomorphies retained from the ancestral waterfowl.

The Cape Barren goose Cereopsis novaehollandiae, potential sister to the coscoroba. Photographed by Norm Hanson.

REFERENCES

Donne-Goussé, C., V. Laudet & C. Hänni. 2002. A molecular phylogeny of Anseriformes based on mitochondrial DNA analysis. Molecular Phylogenetics and Evolution 23: 339-356.

Johnsgard, P. 1965. Handbook of Waterfowl Behavior. University of Nebraska: Lincoln.

Kear, J. 2005. Ducks, Geese and Swans. Oxford University Press.

A Pathetic Plea for Recognition, and a Platypus-billed Duck

The closing date of submissions for this year's OpenLab, an annual collection of the year's best science-blog writting (as judged by the judges), is the 1st of December - a week from today. If there has been anything here at Catalogue of Organisms over the past year (since December the 1st last year), please (please!) submit it for consideration. Please! Go through the archive in the right sidebar, pick out your favourites, and make your contribution towards restoring my fragile sense of self-worth.

Otherwise, your humble host is still fairly knackered after getting back from the field yesterday (two weeks away = nearly three hundred e-mails [mostly spam], 1000+ entries on Google Reader, one pair crossed eyes). So just a brief finishing note:



This is the braincase of Talpanas lippa, a subfossil duck species, about the size of a mallard, described from Kauai by Iwaniuk et al. (2009) in Zootaxa today (and the article is freely available to all comers). As well as the braincase, Talpanas is also represented by pieces of jaw and leg bones and a partial pelvis. The name means "nearly blind mole-duck" - Talpanas would have had small, piggy little eyes, quite unusual in a bird, and would have almost certainly been nocturnal and flightless (flying blind is not usually recommended). Though the complete beak is still unknown, the available jaw pieces indicate that it would have been very broad. The leg bones indicate that Talpanas was a walker rather than a swimmer, so Talpanas was probably a forager for small invertebrates among forest litter; this is the lifestyle currently pursued by the kiwi, another nocturnal bird with relatively small eyes. Iwaniuk et al. suggest that Talpanas also resembled a platypus in using its broad bill to feel for invertebrates amongst the soil. The opening for the trigeminal nerve in the braincase is very large like that of a platypus (it's the opening labelled 'V' on the images above - take a look, it's freaking huge), indicating that Talpanas' bill would have been very sensitive to touch. Unfortunately, the skull of Talpanas is so unusual that its relationships with other anseriforms are obscure.

More From the "They Don't Write Papers Like They Used To" Files

But before that, a couple of other things:

Recent Carnivals - Berry Go Round is here, Circus of the Spineless is here.

Also recently, the Open Laboratory 2008 collection of some of the year's best online science writing is now available. In the interests of disclosing all interests (naturally), yours truly has a piece featured in this publication - on citrus fruit. Anybody who has heard me commenting on my poor knowledge and outright terror of botany will know that this is a Very Funny Thing.

On to the main point of the post, which will not be anything I'm writing at all...

Recently, I was reading a paper from 1866 by a Dr H. Dohrn with the unprepossessing title of "Synopsis of the birds of Ilha do Principe, with some remarks on their habits and descriptions of new species" (Proceedings of the Zoological Society of London 1866: 324-332). Principe, for those who don't know it, is a part of the country of Sao Thomé and Principe in west-central Africa. This is the second paragraph of that publiction:

It seems to me that the most remarkable feature in the fauna of Ilha do Principe is that not a single bird of prey exists on the island, whilst they are abundant on the two other islands and on the nearest part of the continent. I saw hundreds of Milvus parasitus in San Thomé; Gypohierax angolensis and some other species are not uncommon in Fernando Po; but the whole tribe avoids Principe. The inhabitants of the latter place and of San Thomé assert that there is a deadly hatred between the Grey Parrots (Psittacus erythacus) of Principe and the Kites of San Thomé, and that, if ever a Milvus visits the neighbouring island, hundreds of Parrots fall upon him and kill him, and that the Kites take revenge if perchance a Parrot should venture a trip to their kingdom. There must be some family reason for this strange degree of enmity, for they seem to live in tolerable peace together on the coast.

You will probably not be surprised to hear that I was somewhat taken aback by this - even allowing for the different time period, it seemed a rather credulous account. But as I read further, I realised that Dohrn was employing something that is a little alien to modern academic writing: irony.

To demonstrate my point, here are my other favourite passages from Dohrn:

On a species of drongo:

The native name is "Maria Palu, feiticeira" (translated, Maria Palu, the sorceress). The bird is black, with red eyes; seems very indolent in daytime, and shows a great ability in the imitation of some other birds' voices. Of course there must be some "feiticeira" to it: therefore, sitting on the roof of a house and singing in its melancholy manner, it prophecies the death of one of the inhabitants; and this, of course, takes place, but often a long time after this prophecy.

On the bald ibis:

Soon after my arrival on the island I was informed by some natives that there was a very remarkable bird in the island called "Corvão." One told me that it was a kind of raven with splendid metallic wings; another described the bird "with the head of an owl and the feet of a duck, climbing up and down trees;" and others gave me other extravagant descriptions of it; but all of them agreed that the bird lived in almost inaccessible rocky and wooded localities of the southern district, and that if ever a specimen passed over the town it was a bad omen for the white inhabitants, who in such case were exposed to heavy disease or death. Of course I was very curious to see this species, and settled for a fortnight in a negro's hut in those desert parts of the island*. Whoever has visited those large tropical forests knows the difficulty of proceeding there. I enjoyed the special favour of heaven in arriving there when the rains set in a month before they usually do, and it was very hard work to run after these birds. I saw them daily at great distances, and heard them crowing like a Raven; but as soon as I entered the forests the monkeys made so much noise, barking and howling, as to alarm all the animals in the neighbourhood. Thus I was finally very glad when one of my native hunters appeared with a female specimen of the Corvão, which turned out to be Geronticus olivaceus.

*I think in this case "desert" means "deserted", not "arid".

Les is More

The avialan theropod previously referred to here as "Les" has now made its official, honest-to-goodness debut in the latest issue of Nature, and I can now reveal the proper name for Les - Epidexipteryx hui (the genus name means "display feather" and refers to the fact that the feathers preserved for Epidexipteryx appear to have been used for display rather than flight). It's a pretty fossil, but Nature has pulled its usual frustrating trick of giving us just enough information to whet the appetite, and leaving us howling frustratedly for more information...

Reconstruction of Epidexipteryx hui above taken from The Loom.

Let's Have Less of Les

Tom Holtz of the University of Maryland has confirmed via the Dinosaur Mailing List that the fossil animal introduced in the last post as Les is a snafu. The authors of Les intended for their manuscript to be submitted online to Nature, and its arrival on Nature Precedings was a mistake. There is every possibility that the name given to Les in the manuscript will change before publication (pity, I rather liked the name they'd given), and the reviewers may actually recommend that the authors do just that. It is not uncommon practice for reviewers to recommend that authors not use names that are leaked to the public in some way before publication - I suppose to distance the finished product from the rumour mill, though personally I think it probably confuses things even more.

Still, the very fact that such slips can happen so easily just reinforces everything I said in the last post about the need to discuss how the internet affects our concepts of publication, and whether or not we need to adjust our concepts of how to determine priority accordingly.

A New Stem-Bird and Publication in the Digital Age

Scansoriopteryx heilmanni, as reconstructed by Stacey Burgess.

First off, notification of the focus of this post came via the Dinosaur Mailing List.

It is almost a truism that the internet has changed the face of scientific publishing. Online versions of journals have become the first port of call for many, if not most, researchers. The paper reprint has become an endangered species, and articles are exchanged via e-mail as pdfs. Online-based journals such as BMC Biology and the PLoS collection have abandoned the standard journal format with articles collected into issues, and release articles as and when they become available. Even among those journals that still release regular issues, many have begun offering advance online releases of upcoming articles. For most branches of science, these advances are mostly all for the good. Good science, after all, is largely dependent on access to information, and there is much to be said for allowing the dissemination of new information as quickly and easily as possible. However, at least one branch of science, taxonomy, remains firmly attached to the printed page, and has good reasons for doing so.

As alluded to here before, taxonomy differs from other sciences in that it provides the means for communication between biologists working in other disciplines as well as being a target of investigation in its own right. In order to facilitate communication, it makes sense that (a) the taxonomic system should be as stable as possible*, and (b) when conflicting taxonomies do arise, then the means for determining the correct nomenclature to use should be as simple and automatic as possible. It is to satisfy this second requirement that taxonomic systems employ the principle of priority - if two separate names exist for the same taxon, then the correct name to use is the one that was published first.

*Though, as with governments, "stable" in this context does not necessarily mean "unchanging". Rather, it means "not prone to change without proper cause".


Scansoriopteryx again, this time by Matthew Martyniuk.

Of course, saying that the first name to be published is correct immediately raises the question of what counts as publication. The International Code of Zoological Nomenclature (Article 8) requires that a published work must be issued in a permanent format, and must be generally made available upon publication. These are pretty broad criteria, but any work (and any new names within) cannot be considered published until they are met. The date at which these criteria are met becomes the official date of publication. Release of an article online (such as in a pre-print) does not count as publication in this sense because a webpage is not permanent. While a book requires little or no attention once it has been accessed in a library and can sit there more or less indefinitely*, a webpage requires continual upkeep to remain available. The ICZN does allow a name to be published online if some form of permanent copy (such as a print-out or CD) of the webpage is deposited in a number of major public libraries (such as the American Library of Congress). As far as I know, the Botanical Code still insists on printed publication.

*Okay, theoretically a book may be at risk of decaying after a few hundred years, but that's still pretty permanent compared to a website.

In June last year, the Nature group launched Nature Precedings, an online repository for preliminary findings and manuscripts, allowing researchers to share data of interest that might or might not be sufficient for an eventual completed paper, obtain feedback on said preliminaries that might improve the final manuscript, and just generally keep other researchers informed on what was going on. Entries on Nature Precedings are not peer-reviewed before becoming available, and are generally not regarded as completed publications. A few days ago, a new entry was loaded on Nature Precedings by Zhang et al. describing a decidedly interesting new dinosaur species, complete with attached name. Officially, this taxon is not yet published. Because of the interest that surrounds any new dinosaur discovery, you can bet your ass that that won't stand in the way of its becoming widely known.


The new scansoriopterygid, which I'm calling Les. Figure from Zhang et al.

As I said, there's a name attached to the new taxon. It's a very nice name, too - kind of rolls off the tongue. But because I'd rather avoid using an unpublished taxon name, I'm keeping shtum (of course, click on the link and you'll find the name right away, so my protest is really pretty pointless). Because the new species is a member of the family Scansoriopterygidae, I'm going to call it LES (standing for "Looks like Epidendrosaurus or Scansoriopteryx"). Les was a small bird-like theropod about the size of a pigeon, and represented by a very nice nearly-complete skeleton, complete with preserved feathers including a tail of four long ribbon-like feathers that were about as long as the rest of the animal. Phylogenetically, Zhang et al. position Les as more closely related to modern birds than the dromaeosaurs (Velociraptor et al.) but less closely related than Archaeopteryx. Les is exactly the sort of thing that might eventually be published in Nature, and its appearance in Nature Precedings gives the impression of leading into doing so.

The family Les belongs to, Scansoriopterygidae, has become something of a poster child for the issues surrounding online publication. Two genera have previously been named for scansoriopterygids, Scansoriopteryx and Epidendrosaurus, but most researchers suspect that these two names refer to the same animal. Unfortunately, determining which of the two names has priority is not a straightforward question, as discussed by Harris (2004). Both names were published in 2002, but the book naming Scansoriopteryx was probably less widely read than the journal naming Epidendrosaurus. Epidendrosaurus appeared in an online preprint on the 21 August, but the printed version didn't appear until 30 September. The exact date of publication of Scansoriopteryx is a little debatable, but it seems to have become available by 2 September - after the name Epidendrosaurus became widely publicised online, but before the official publication of Epidendrosaurus. Technically, Scansoriopteryx has priority, even though Epidendrosaurus was the name that became known to the public first.

The lesson from cases such as Scansoriopteryx is that the time has well and truly arrived for us to re-evaluate what it means for a name to be "published" in the digital age. In the past, the first a public would generally hear of a manuscript and its contents was when the finished publication arrived in all its official glory. Now, as demonstrated by Les, it may be possible for a manuscript to appear online as a rough draft, as a polished pre-print, as the final official product. Should these early appearances be regarded as valid publications? When the manuscript first appears, or only as it approaches its final form? The initial format for publication of Epidendrosaurus may not have been permanent, but should we regard the later appearance of a permanent printed edition as having validated that initial appearance? The rules of the game are changing. It is time to decide whether we should keep playing.

REFERENCES

Harris, J. D. 2004. 'Published works' in the electronic age: recommended amendments to Articles 8 and 9 of the Code. Bulletin of Zoological Nomenclature 61 (3): 138-148.

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.

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.

How Irritable is This Bird?

Jackass penguin (Spheniscus demersus). Photo by Tuxette.

It's definitely intriguing how the meanings of words can change over the years. A Blog Around the Clock recently presented a quote that claimed that Charles II described the newly-built St Paul's Cathedral as "awful, pompous and artificial". This was entirely complimentary - "awful" indicates something that inspires awe, "pompous" roughly means "majestic", while "artificial" means that it indicated a great deal of artifice on the part of its builder - and "artifice" would have meant "technical or artistic skill", having not yet gained its current connotation of duplicity and deception. "Automaton" is another word that has changed significantly in meaning. It literally means "self-moving", and so when it was first coined would have indicated the independent, undirected movement and action of the subject - almost the complete opposite of its current usage.

I bring up those examples to segue into another change in meaning that I came across yesterday. I happen to have in front of me a copy of the Proceedings of the Zoological Society of London for 1866, in which (amongst other things) W. Lilljeborg presented a revised classification for birds. In explaining the principles on which he based his classification, Professor Lilljeborg notes:

Irritability seems to us to be the most distinguishing character for birds, and this should consequently be taken into consideration more than others with regard to their classification.

Canada goose (Branta canadensis). Photo by George K.

I'm sorry? You're classifying birds according to how irritable they are? Fortunately, Lilljeborg further explains, "We do not by irritability mean the muscular strength alone, but vivacity and activity generally". Lilljeborg was basing his classification on a principle that evolution had proceeded from less derived, more sluggish forms to more derived and accomplished forms. All horribly Scala Naturae-based, of course, and more than a little inaccurate in some regards:

The swimmers seem to us the lowest, from their showing a tendency to the lowest form of vertebrated animals - the fish-form. In the [penguins], where the wings resemble fins, and where they, as in all other diving birds, serve as such, we have this form most strongly designated. The heavy, clumsy structure, with small wings and short legs, also makes them generally less active than other birds, and shows a lower development of the type of bird.

Southern yellow-billed hornbill (Tockus leucomelas). Photo by Tuxette.

A description obviously heavily biased by observations of penguins almost solely on land, not in the water where they are far more adept. I also had to snicker somewhat at Lilljeborg's complaint about the previous tradition of placing the birds of prey (rather than the passerines he favoured) at the "summit" of avian evolution:

A system that places the dirty vultures highest, does not seem to us to indicate a correct idea of the nature of birds.

Great blue heron (Ardea herodias). Photo by tofrg.

Lest I give you too negative impression of Lilljeborg's skills as a systematist, his final classification stands up fairly well by the standards of the time. The classification itself was generally based on good anatomy - the philosophical considerations mostly affected what order he listed things in. Still, I couldn't read that section on "irritability" without getting the mental image of Professor Lilljeborg, his fingers heavily bandaged, making his way down a row of birds sitting in cages, poking each one in turn with a chopstick and seeing how long it took to snap back. One suspects he probably left the eagle until last.

REFERENCES

Lilljeborg, W. 1866. Outlines of a systematic review of the class of birds. Proceedings of the Zoological Society of London 1866: 5-20.

Taxon of the Week: Leg or Breast?

This week's highlight taxon is one that is very familiar to me as a New Zealander, except it's not really. I've heard of these creatures since I was a little lad, and representations of them have been almost everywhere I've gone. I've never actually seen one. I don't know anyone who's every seen one. Probably no-one has seen one for hundreds of years, in fact. The Dinornithiformes are but a memory these days, long since converted into quarter-pack meals for Polynesian settlers. Ka ngaro i te ngaro a te moa - lost as the moa is lost.

The taxonomy of moa is complicated, but at present there are eleven species recognised as valid*. The order was unique to New Zealand - the "Australian" Dinornis queenslandiae De Vis, 1884, was based on a partial femur in the Queensland Museum, but this bone is now believed to have come from New Zealand and is assigned to Pachyornis elephantopus. In the past, Dinornithiformes has been divided into two families - the lightly built, more cursorial genus Dinornis in its own family and the other smaller and/or more heavily built genera in the Emeidae, but phylogenetic analysis has shown that Dinornis is nested within the Emeidae (Worthy & Holdaway, 2002).

*Eleven species were recognised in Worthy & Holdaway (2002), the most recent major review of Dinornithiformes. Bunce et al. (2003) reduced the number of species of Dinornis from three to two (see below), but Baker et al. (2005) increased the number of species of Megalapteryx from one to two.

The photo at the top of the page (from Wikipedia) shows the reconstructed Dinornis in the Auckland Museum. This specimen has been around for some time - it was built in 1913, though when the Natural History section of the museum was rebuilt it lost the tussock-land diorama it had previously inhabited (if I recall correctly) and moved into a glass case. The Auckland Museum moa stands about three metres tall, and modern interpretations would, unfortunately, label this a severely inaccurate reconstruction. It has been mounted in an unnaturally elevated stance, and should have been much more low-slung. A more realistic reconstruction was shown on a recent stamp issue, shown below (from New Zealand Birds):



Such a lowered reconstruction significantly lowers the height, but we're still looking at about two metres for the tallest Dinornis specimens. A moa of this size may have wighed over 150 kg (Worthy & Holdaway, 2002). Other species were smaller - the smallest was Megalapteryx didinus at probably about 40 kg. The super-heavy Pachyornis elephantopus was considerably shorter than large Dinornis, but may have weighed about the same amount. The image below comes from Nature, and shows three moa species against a 1.8 metre tall human. From left to right, the moas are a female Dinornis novaezealandiae, Megalapteryx didinus and Pachyornis elephantopus.



Despite their extinction prior to European settlement in New Zealand, a surprising amount of molecular data has been gleaned from ancient DNA studies of moa. Among other things, said molecular analyses have demonstrated that Dinornis displayed the highest degree of size dimorphism known from any bird (Bunce et al., 2003). Previously Dinornis had been divided into three species on the basis of size. Bunce et al. tested DNA from Dinornis remains for female-specific markers (birds differ from mammals in that it is the female that possesses different sex chromosomes [ZW], while the male has identical sex chromosomes [ZZ]). They found that all specimens that had been assigned to the smaller 'species' Dinornis struthoides were male, while all specimens of the larger 'species' D. novaezealandiae and D. giganteus were female. Molecular phylogenetic analysis also showed that these specimens were intermingled, with the major divide in the genus being not by size but by geography - the North Island and South Island populations (both containing representatives from all three 'species') were distinct, and were recognised as the separate (but morphologically indistinguishable) species Dinornis novaezealandiae (North Island) and D. robustus (South Island). While females showed a great deal of variation in size, the largest females would have been about 280% of the weight and 150% of the height of the largest males.

There is very little reliable information on the life habits of moa. By the time of European settlement, it had been long enough since the extinction of the moa that records of it in Maori oral tradition were seemingly few and far between, and those that were present had become significantly mythologised. Early researchers such as Owen and Haast interpreted moa as birds of open country, comparing them to modern ostriches and emus. However, the extensive New Zealand grasslands and fernlands these authors pointed to hadn't existed prior to human settlement, so moa were undoubtedly forest birds, foragers rather than grazers as also shown by preserved gizzard contents. Dinornis and Pachyornis seem to have had more fibrous diets with gizzards containing twigs and fibrous plants such as Phormium (the New Zealand flax) while Emeus and Euryapteryx with less robust bills had more selective diets of fruit and leaves. Interestingly, a well-preserved specimen of Euryapteryx geranoides showed a massive intrathoracic loop in the trachea, 1.2 metres long. In other birds such loops are associated with the ability to make loud, far-carrying calls, so moa (or at least Euryapteryx) would have been quite vocal birds in life.

REFERENCES

Baker, A. J., L. J. Huynen, O. Haddrath, C. D. Millar & D. M. Lambert. 2005. Reconstructing the tempo and mode of evolution in an extinct clade of birds with ancient DNA: The giant moas of New Zealand. Proceedings of the National Academy of Sciences of the USA 102(23): 8257-8262.

Bunce, M., T. H. Worthy, T. Ford, W. Hoppitt, E. Willerslev, A. Drummond & A. Cooper. 2003. Extreme reversed sexual size dimorphism in the extinct New Zealand moa Dinornis. Nature 425: 172-175.

Worthy, T. H., & R. N. Holdaway. 2001. The Lost World of the Moa: Prehistoric life of New Zealand. Indiana University Press: Bloomington (Indiana).

A Frustrating Giant Bird

Darren Naish in a recent post on his most excellent Tetrapod Zoology blog on a completely different subject mentioned the giant fossil bird Eremopezus, which inspired me to look it up (I was nearly inspired to change subject by watching a bagmoth in the lab here sealing itself into its bag in preparation for pupating, but another time, perhaps...)

Eremopezus is known from leg bones from the upper Eocene of the Fayum of Egypt. The most recent review is by Rasmussen et al. (2001), but it was first described in 1904. Lambrecht later divided the then-available material into two genera, Eremopezus Andrews 1904 and Stromeria Lambrecht 1929, but there is little significant difference between material assigned to the two and they are now regarded as synonymous.

Being a giant landbird, Eremopezus was originally thought to be related to modern giant landbirds, the ratites. Ratites are a group of flightless birds distributed between the southern continents - the ostrich (Africa), rheas (South America), emu, cassowaries (Australia), moa and kiwis (New Zealand). Arguments have run back and forth about whether the ratites are monophyletic, or have arisen independently from different ancestors. Recent molecular phylogenies have been pretty much unanimous that the ratites are indeed monophyletic, and together with the flighted tinamous (Tinamidae) are the sister group to the remaining modern birds. On the basis of a prominent ridge on the tarsometatarsus, Lambrecht (1933) suggested that Eremopezus was related to the elephant birds (Aepyornithidae) of Madagascar.

The problem is that this is simply not very significant evidence, as pointed out by Rasmussen et al. (2001). Large flightless birds show a great deal of similarity in the form of the leg bones, due to similar functional requirements. The flightless carnivorous bird Diatryma has hindlimb bones indistinguishable from those of ratites, despite being more closely related to the modern Anseriformes (ducks and geese). Rasmussen et al. concluded that Eremopezus could not be reliably associated with any other known group of birds.

To add to this, Eremopezus showed a number of distinct features all of its own. It appears to have been a fairly lightly-built bird, but slightly larger than a cassowary or rhea. The distal end of the tarsometatarsus is markedly flattened dorsoventrally, and the trochleae (and hence the toes) are quite widely splayed (an attachment scar indicating the presence of a hallux - the rear-pointing toe - is present, but this was probably small as an adaptation for terrestriality). The trochleae on either side have relatively light grooves, suggesting that the toes were quite mobile. The modern birds with the most similar morphologies are Sagittarius serpentarius (secretarybird) and Balaeniceps rex (shoebill). Both these birds use their feet for manipulation - Sagittarius is a ground predator that catches prey with its feet, while Balaeniceps uses its feet to grasp floating vegetation in swampy habitats. The Fayum of the Eocene also appears to have been a quite swampy habitat, but the appeal of a gigantic secretarybird is not to be denied. In the meantime, we simply have to wait on further remains to turn up before we can say more on the subject.