A Whole Crock of Crocs
Life took yet another little detour this weekend as Tito once again worked through a crisis. His gums and tongue were pale, he refused food and water, and he was listless and could hardly stand. The vet said he was bleeding internally somewhere, but since he didn’t show distress at all, just weakness, I thought I’d give him just one more day for all the great doggy dreams he seemed to be having. And damn if he didn’t start drinking Sunday night. Monday he took solid food, and today we walked a good half-mile together in a local park. He was slow of course, but really enjoyed himself, rolling in and eating the snow, peeing on every bush in sight, and even trying to solicit play from another dog a mere 12 years old. As hard as he is on my sleep and work, he’s inspiring.
Last week, see here and here and here, there was a paper published about a new and bizarre species of early crocodile relative (poposaur) that was found in a plaster-jacketed slab of fossilized bone from New Mexico’s Ghost Ranch quarry. It had been at the American Museum of Natural History in New York for decades. Named Effigia, this little (6-foot) late Triassic animal was toothless and a biped!
Since I was up much of the night anyway Friday and Saturday, I thought that even though Effigia lived well outside the time-frame that Olduvai was dedicated to, I’d try a little reconstruction based on the bone and skull drawings available on-line. Here’s the result.
That reminded me of an early Cretaceous vegetarian crocodile from Mongolia’s Gobi desert that I painted for Discover magazine back in 1997. Here’s that little acrylic piece.
The animal is called Chimerosuchus, and was small (3-foot), terrestrial, and long-legged. It also sported four spatulate “buck” teeth. I was lucky with this painting in that I had one of the world’s experts on fossil crocodiles as my guide. In fact it was Han-Dieter Sues who had solved the question of exactly what group the little creature belonged to. As with Effigia, it was the unique structure of the ankle that was the first clue.
Today, crocodilians fill only a small amount of the ecological space that they occupied at various times in the past. All are ambush predators, scavengers, or fish eaters today. Two of the most unusual are the gavial or gharial (Gavialis gangeticus) and the false gavial (Tomistoma schlegelii). As the common names indicate, the long and narrow jaws of these two crocodiles were thought to be the result of convergent evolution. Genetic and new morphological studies however show them to have a common narrow-snouted ancestor.
This digital illustration was the cover of the June 2003 issue of the journal Systematic Biology. A detail of the gavial’s head shows that it was one of my earlier attempts with Photoshop.
The original was done at 600 dpi and was an enormous file. It needed to be as I actually counted thousands of scales from about 30 different photos and scientific drawings to make sure my animals were accurate. I also had to change my layout rather late in the process, because the initial measurements I had for the cover were wrong (my fault). Tomistoma was rising to take a small animal from the surface of the water and I had to leave the victim off.
For a brief but well-written look at Croc evolution and that unique ankle joint, take this link to Tim McDonald’s (afarensis) ” Transitions” site.
The Florida Museum of Natural History has a wonderful site on all the living Crocodilian species. I’ve linked the pages of the two featured in my painting, but here is a link to the introduction page. Lots of information.
February 1st, 2006 at 12:56 am
Great post! I love the new Effigia!
February 1st, 2006 at 2:21 am
Beauties!
Isn’t there also a pigmy gavial of some sort?
February 1st, 2006 at 10:27 am
Crocs!!!!!!!
Glad to hear Tito enjoyed the snow.
February 1st, 2006 at 10:45 am
coturnix: I’ll freely admit to knowing a lot more about birds and mammals than these guys, but in doing the research for the SysBio cover I only found reference for only one extant species of gavial. According to Steve’s research on “Transitions” however, they’ve been found as fossils as far back as the late Oligocene, so it’s possible there might well have been a pygmy species in the past.
February 1st, 2006 at 10:47 am
Tito is lucky to have such a good Friend. Are you still near Flagstaff?
Great drawings Sandy
February 1st, 2006 at 12:05 pm
Crocs!
Olduvai George does it again: another gorgeous, art-filled post on ancient and modern crocodiles, including a reconstruction of the recently discovered Triassic Effigia….
February 1st, 2006 at 12:55 pm
Whoo, more absolutely wonderful art…
IIRC, the false gavial was thought to be a tomistomine crocodylid, while the gharial was in a family of its own. You wouldn’t by any chance have the reference where the false gavial is supposedly shown to be closely related to the gharial, would you?
Interestingly, whatever their affinities, it seems that the false gavial and gharial are both relicts of two crocodilian lineages that were much more widespread and diverse in the past.
February 1st, 2006 at 1:07 pm
Hey, thanks for the link to Transistions. Beautiful art work, as always!
February 1st, 2006 at 1:13 pm
As always, great stuff. Thanks!!!
February 1st, 2006 at 1:45 pm
Great to have you back at ‘em, O’George!
February 1st, 2006 at 3:09 pm
Hai Ren : Both of the references were from the June 2003 issue of the journal I did the cover for, Systematic Biology.
True and False Gharials: A Nuclear Gene Phylogeny of Crocodylia
(Harshman et al.)
Combined Support for Wholesale Taxic Atavism in Gavialine Crocodylians
(Gatesy et al.)
February 1st, 2006 at 4:50 pm
very interesting piece, carl, and as always, lovely drawings!
February 1st, 2006 at 8:57 pm
Awesome! Truly awesome!
Thanks for putting up your drawings for us to enjoy.
February 1st, 2006 at 10:48 pm
“Tito is lucky to have such a good Friend.”
Most assuredly, Sandy. Every dog should be as fortunate.
Effigia looks splendid, OGeorge. Between it and Chimerosuchus It leads me to imagine what your take on the therapsids might be like. Not meant as a hint; it’s just those freakies fascinate me. (-;
February 1st, 2006 at 11:03 pm
Awesome crocodilians, those gavials are great…..remind me of the “super” croc, Sarcosuchus imperator that Paul Sereno was studying
Also, thanks for the kind words on my blog
February 2nd, 2006 at 12:32 am
[...] And just today, a killer restoration in an article on the diversity of crocodiles and their relatives over at Olduvai George. File under Recent Discoveries. Posted by Matt Celeskey round about 10:25 pm. [...]
February 3rd, 2006 at 12:44 pm
Enjoyed the art, the info, and the crocodylian tidbit at Transitions. The last helped me decide on some background for an exercise in imagination I’m working on.
To explain: I’m creating a world where dragons exist. I’ve already decided that dragons are descended from a thecodont ancestor, but their relationship to the other thecodont derived orders remained mostly unclear. Learning about crocodylian ankles helped clarify matters.
In short, dragons have an ankle structure much like that of crocodylians, if a bit more derived than the latter. There are other differences structurally, indicating a common thecodont ancestor rather than a suchian one. It should be noted that in some respect the dragon ankle is actually more primitive than the crocodylian, while, at the same time, incorporating advanced features that result in the same utility as crocodylians enjoy.
And so an exercise in fantasizing gains a greater degree of depth and versimilitude than it would otherwise enjoy without science.
In important matters, I hope Tito is doing well and enjoying life. Tell him I said hi, and give him a good head skritching for me.
February 10th, 2006 at 2:54 pm
Superb drawings and glad Tito is feeling better.
Mik
March 10th, 2006 at 4:37 am
I’ve just found this blog and I already love it!
Simply wonderful.
Thanks Carl for all that, it’s so fascinating…
Greetings from Italy :O)