Wednesday, January 20, 2010

Roots

I've always been fascinated by roots. If something is interesting in its own right, where it came from is usually even more interesting to me. This probably explains my fascination with archeology and linguistics; I don't really think that they're all that exciting in their own right, but the idea that our culture, plus plenty of others, came from an Eneolithic culture on the steppes of the Ukraine and spread throughout much of Europe and Asia from there to have a profound impact on the history of the world, is fascinating. Tracing the rise and spread of this ur-culture, and its subsequent dispersal and dissolution into various descendent cultures is endlessly fascinating to me because of my obsession with roots, not because I think language drift and pottery sherds are really interesting all on their own.

The same reason probably underlies with fascination with paleontology, as well as my love of the Triassic in particular. Dinosaurs are really cool. I've always thought so, literally as far back as I can remember. My first memory of ever going to the public library in the town I grew up in, before I'd even started kindergarten or anything, was picking out a book on dinosaurs. Illustrated by Rod Ruth. The first book that I remember clearly owning, that my parents bought just for me, and not for "the kids" generically, was the Little Golden Book of Dinosaurs, illustrated by William Rutherfoord.

In any case, knowing my predilection, you can imagine that it T. rex, Triceratops, Stegosaurs, Diplodocus and all the rest are cool, then I'd be fascinated with the arrival and rise of dinosaurs in the Triassic. And indeed, I am. The Triassic is a wonderful time for roots. Following immediately on the heels of the greatest mass extinction the world has ever known, it was a time when life was doing all kinds of interesting things and all kinds of roots were laid down in the Triassic that are still with us today.
I talked a bit about it a few days ago when I blogged about Tawa hallae, but we've actually been discovering a lot of stuff about the Triassic just recently, and finding that our picture of that landscape was incomplete and inadequate. Five years ago, we had no idea what a revueltosaur or a silesaur was, but now we're finding that both were hugely important faunal components of the landscape all over the world.

Perhaps most importantly, in the last two decades or so, our knowledge of the very earliest dinosaurs, as well as the closest relatives; the "almost but not quite" dinosaurs has increased by leaps and bounds. Nobody much had heard of Herrerrasaurus or Lagosuchus, in part because their remains were too scant and too incomplete to mean a heckuva whole lot. Paul Sereno partly filled that gap by recovering new, much more complete Herrerrasaurus remains, as well as discovering little Eoraptor.

Interestingly enough, although Eoraptor and Lagosuchus are on opposite sides of the great divide; i.e., one is a dinosaur and the other not, in practical terms, you or I seeing them side by side running around in the fern brush, or in a paleontological zoo, probably wouldn't be able to tell them apart.

The images below are not the most cutting edge, but they give you a good idea of what I'm talking about. See if you can tell which is which. Well, see if you could without the label on the one, anyway.

I also listened recently to part of a webcast by the National Science Foundation where Sterling Nesbitt (one of the co-describors of Tawa) talked about the find, and he was asked specifically about the feathered appearance that they chose for the reconstruction. He went with the very sensible (in my opinion) tack that if some therapods were known to have feathers, and a heterodontosaur appears to have had something like a feather fringe, then most likely some kind of dermal or epidermal integuement (a fancy way of saying, "we don't want to stick our necks all the way out and say that they're actually feathers, but they look like feathers") was ancestral to the dinosaurian condition. Therefore, Eoraptor and even proto-dinosaurs like Lagosuchus may well have had them too.

Too bad I couldn't find the older Greg Paul illustrations of feathered Lagosuchus scanned online somewhere, but I can't so...

1 comment:

Joshua said...

Although this is actually old news, it was new to me: Sterling Nesbitt, part of the team that described Tawa hallae, published a paper in 2001 that purports to be a herrerrasaurid pubic boot (a part of the hip bone structure of dinosaurs) from the Anisian of the Middle Triassic. If so, this would be the earliest known dinosaur fossil, and would in fact predate, or at least be contemporaneous with the famous Chañares formation that has most of the famous pre-dinosaurian dinosauriomorphs like Lewisuchus, Lagosuchus, and others.

Although... that wouldn't be too surprising. The earliest known dinosaur fossils other than that would be the Ischigualasto fossils; Eoraptor, Herrerrasaurus, Pisanosaurus and Panphagia which are from the earliest Carnian. Because they already show some degree of diversity, we know that they can't literally be the earliest dinosaurs... they're just the earliest we know so far. Put pushing the arrival of dinosaurs back ten million years or so from the earliest fossils we have now... not too unexpected.

I hope more of Nesbitt's find turns up some day.