Tet Zoo picture of the day # 7

i-7f9fa60ae55055c62c9b788df420503a-Subhyracodon resize.jpg

Yet another rhino - there is an inadvertent theme going here. This amazing fossil is an embryo of the diceratheriine Subhyracodon occidentalis from Upper Eocene-Lower Oligocene USA (Subhyracodon often went by the name Caenopus in the older rhino literature). Discovered in rocks of the Brule Formation in Wyoming, the baby was (reportedly) not recovered from the body of a mother, but found on its own. Its total length is 76 cm. As an adult, Subhyracodon was a big tridactyl rhino as much as 4 m long. It was hornless, but males possessed paired ridges on their nasal bones. Good news everyone: posts (yes, posts) on multiple new living mammal species to appear later today. Stay tuned...

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[blink] So this "stillborn embryo" was 20-25% of adult size? Sorry, but there's something I don't understand here. It was preserved in the fetal position. If it was stillborn and preserved just after birth, does that mean it passed through the pelvic canal in the fetal position? And it was nearly full size at the time? Does a female Subhyracodon have a large-enough pelvic canal to permit that?

By wolfwalker (not verified) on 01 Jun 2007 #permalink

Yeah, I don't get it either (the fact that the limbs are curled up show that the baby has not passed through a birth canal). When I mentioned the stillborn thing, I initially wrote that 'it has been suggested by some that it was stillborn'. Does anybody know any more about the history of this specimen? I've a feeling it was collected commercially (the photo shows a commercially available cast of the real thing)... On balance, a curled-up embryo like this must either have been preserved within a mother, or it must have somehow found its way outside of the mother without going via the birth canal. Predators will pull unborn embryos out of course, but tend not to leave them in a pristine condition.

Where does the photo come from? There's both Chinese and Korean on it.

By David Marjanović (not verified) on 01 Jun 2007 #permalink

amazing. Was it on display at a fossil show or convention? If it is commercial, I suggest asking the Black Hills Geological Research Institute guys, Neal or Pete Larson or Bob Farrah for info. Is the specimen White River Oligocene? Can also ask Mike Triebold of the Dinosaur Resource Center in Woodland Colorado. The commercial folks are providing an awful lot of material to the scientific community, and these guys likely know everything that happens everywhere.

By Donald Wolberg (not verified) on 01 Jun 2007 #permalink

Silly question here, but it seems there are a couple of ways the baby rhino could have come to be in the fetal position: 1) curled up in its nest or sleeping place, and killed by volcanic gasses, starvation, or cold, 2) found by the collectors in some other position and then put into a "cute" fetal position for display.


By Noni Mausa (not verified) on 01 Jun 2007 #permalink