Dispatch from the Permocarboniferous—Temnospondyls
1:06 am
The temnospondyls were a stubborn group of early amphibians who refused to part with portions of their anatomy that they had inherited from their aquatic ancestors. While their contemporaries were overhauling their fish-grade physiques to take advantage of opportunities available on dry land, the temnospondyls looked at their newly evolved hands, threw them up, and crawled back into the nearest river in an attempt to thwart evolution through sheer amphibious obstinacy.
I am, of course, exaggerating. Temnospondyls were subjected to the same forces of modification and selection that shaped every other animal lineage, and throughout their long dynasty they did undertake some noteworthy evolutionary experiments. But they are unusual in that they retained the complex, multi-part vertebrae and intricately folded teeth that most other backboned animals modified shortly after making the transition from surf to turf. And looking at the flat, toothy, textured skull of a temnospondyl, one gets the impression that instead of wasting their time adapting to their environment, they had decided to hunker down and force their environment to deal with them.
Eryops, shown here lunging after a xenacanth shark, exemplifies the niche that temnospondyls returned to time and time again—that of the “crocamander” or “frogodile”. Long before the first alligators swam through any prehistoric bayou, Eryops and its kin were cruising the Carboniferous waterways. One hundred million years later, when dinosaurs first appeared, a group of temnospondyls called metoposaurs were still prowling the swamps, snapping at prey with heads so broad and flat that they resembled sharp-toothed toilet seats. And one hundred million years after that, when true crocodiles had muscled in on their territory in most of the world, the last of the”crocamanders” were still hunting in the relatively isolated waters of Australia.
Eryops is typically pictured as a squat, fat beast with a large, frog-like head and a somewhat insipid grin. This is probably not entirely inaccurate. However, restorations such as these fail to show the dozens of sharp, recurved teeth that line the edges of its mouth, or the extremely nasty-looking fangs that projected from its palate (a trait shared by all tempnospondyls). This portrait of Eryops, inspired by a skull collected from the Permocarboniferous of New Mexico, was drawn with those features in mind.
More temnospondyls to come…
[...] But I really want to promote Bulletin 31, The Permian of Central New Mexico. As you might guess, this is a smaller, more focused collection of papers, and it reviews the current state of research in New Mexico Permian localities that are still producing fossils after a century of exploration and collecting. Several of the pen-and-ink drawings displayed in our Dispatch from the Permocarboniferous posts are published in this volume, including a nice toothy Eryops on the front cover (the skull that inspired the image is described inside). [...]