Some History of the History of Tetrapods

Titanophoneus potens, a Permian synapsid (image from Kheper).

Benton, M. J. (ed.) 1988. The Phylogeny and Classification of the Tetrapods. The Systematics Association Special Volume 35A & 35B. Clarendon Press: Oxford.

One interesting thing about comparing different fields of research is the different time-scales we work in when it comes to what constitutes a "recent" publication. As an invertebrate taxonomist, I think nothing of delving into stuff that was written in the 1950s or even earlier. A developmental geneticist is likely to regard anything more than a few years old as ancient history. Vertebrate palaeontology lies between these two extremes, but certainly 1988 was a long time ago for the tetrapods.

As a result, I suspect that Phylogeny and Classification of the Tetrapods can't really tell us much about the current state of tetrapod classification. What does make it interesting, though, is what it says about the state of vertebrate palaeontology at the time. The late 1980s were certainly interesting times, not just in vertebrate palaeontology but in systematics in general. The cladistic revolution was gathering speed. Molecular phylogeny was making its first faltering steps, and challenging a few orthodoxies.

The Phylogeny and Classification of the Tetrapods was published in two volumes, and even that says something about changes in focus since. The second volume was devoted entirely to the mammals (about 5,400 living species). Everything else - amphibians, reptiles, birds, about 24,000 living species - took up only the first volume. Birds in particular warrant a single chapter, as do living amphibians (that latter point possibly hasn't changed much). Dinosaurs (the non-birdy type, that is) barely rate a mention. The dinosaur renaissance was in its early stages at the time - for comparison, Bakker's The Dinosaur Heresies, a book I personally don't think much of but which became something of a focal point for changing views on the big lizards, was first published in 1986. (It was also in 1988 that Gregory S. Paul's Predatory Dinosaurs of the World first hit the shelves, in which Paul copped a certain degree of ridicule for his decidedly heterodox reconstructions of dinosaurs covered in feathers - Paul has since, of course, been able to carry around a big bag of harsh words and force his critics on this point to eat them.) Of course, it should be noted that despite its palaeontological bent, ultimately the main focus of Phylogeny and Classification of the Tetrapods is on the relationships between living tetrapods.

Despite all that has changed since then, some parts of Phylogeny and Classification of the Tetrapods seem somewhat prescient. Not so much the molecular chapters - that on molecular phylogenetics of tetrapods as a whole has the grim figure of the Haematothermia clade (birds and mammals to the exclusion of reptiles) rear its ugly head, though the authors at least had the sense to recognise this as probably convergence rather than the actual state of affairs. But the mammalian molecular phylogeny chapter gives us some of the early glimmerings of the Afrotheria hypothesis, though that clade was not to be formally recognised until some years later, while the Novacek et al. chapter on the morphological phylogeny of modern mammalian orders is noteworthy for not finding any support for Ungulata.

The prize for best statement in the book, however, has to go to Gaffney & Meylan's chapter on turtles, where, after a description of the apomorphies connecting turtles to their supposed nearest relatives (the captorhinids, in this case), the authors note "And so we reach God's noblest creature - the turtle".