As you might have noted, I posted an update to my reading. I covered some popular works on a few different books. Some were history. Some were sociology. Some science fiction. Most were Deep Time related. One of those was Dinosaurs of Darkness. This book was about the paleontological escapades of Drs Rich and Vickers-Rich in working in Australia in Early Cretaceous sediments. They had some very eyebrow raising things that they did for their work; they had some even higher eyebrow raising finds; and they had some double eyebrow raising assertions about their work. They freely admit a bunch of it is outlandish speculation. However, let's go over some of the ones that were interesting as far as their work and their speculations.
The first and most solid bit of discoveries that I found interesting was the the paleoclimate work. The Dinosaur Cove site, if I am not mixing them all up, had evidence of permafrost. Considering this was Early Cretaceous, that's fascinating. A researcher from Russia helped to confirm this. In fact, the data from the oxygen 16/18 ratios indicated that the average temperature was a -2 C! Now to be fair, they did state they were unsure if the temperatures were coinciding with the occupation of the environment by dinosaurs or not. However, there were two bits of interesting evidence that supported that the dinos were around. The first is the more famous one: Leaellynasaurus has very large eyes for a hypsilophodontid. This suggests that it was adapted to see in the dark of the Southern Polar Winter where the sun would never rise. Additionally, an orinthomimosaur was found to have periods of arrested growth in its bones that would fit with the hypothesis that they hibernated during that same winter.
Another interesting bit is that they have found what they claim are two ulna from a protoceratopsid. It is supposed to be very similar to, but not the same as, one from a Leptoceratops. They are close enough that they speculated that if they had been found in any part of the former Laurasia then they would have just been assigned to Leptoceratops. This would be the first report of a ceratopsian of any sort in Gondwana. The fact that it is a protoceratopsian, instead of, say, psittacosaur earlier than any known protoceratopsian...well, let's just say that's a little surprising. Twere I a professional I'd be wondering about that identification since it casts a hugely questionable light on the accepted evolution of the ceratopsians. That wouldn't be so bad - new evidence changes our perceptions of the past and evolution - except that it has a rather different than - and contradictory to! - what the fossil evidence supports to date.
(saved from a very disreputable site, if someone has a cite...)
It gets stranger than that still. You see, they also found a placental mammal: Ausktribosphenos nyktos. They state that A nyktos is closely related to hedgehogs and that those are closely related to primates (which is weird: I've not heard that from any other place in my life, but bare with me). They suggest that the pre-primates actually originated in Australia (!!!) and that through a case of a microplate being shed from NorOz to drift north to Laurasia where the critters carried would go on to the evolutionary history we now know. They call it the Noah's Ark scenario.
The holes that I can see are that the hedgehogs, last I checked, were not that closely aligned with primates. Second, since the ulna found that have been tentatively identified as ceratopsian lacks a complete skeleton or even anything more than the two ulna, it seems possible this might be something else. Finally, what of psittacosaurus? That was close to being the most basal of the ceratopsians, iirc. That has only been found in Asia, which would hint that Asia is the source of the ceratopsians.
This whole scenario seems really out there, honestly. Interesting, to say the least , but really out there.
The first and most solid bit of discoveries that I found interesting was the the paleoclimate work. The Dinosaur Cove site, if I am not mixing them all up, had evidence of permafrost. Considering this was Early Cretaceous, that's fascinating. A researcher from Russia helped to confirm this. In fact, the data from the oxygen 16/18 ratios indicated that the average temperature was a -2 C! Now to be fair, they did state they were unsure if the temperatures were coinciding with the occupation of the environment by dinosaurs or not. However, there were two bits of interesting evidence that supported that the dinos were around. The first is the more famous one: Leaellynasaurus has very large eyes for a hypsilophodontid. This suggests that it was adapted to see in the dark of the Southern Polar Winter where the sun would never rise. Additionally, an orinthomimosaur was found to have periods of arrested growth in its bones that would fit with the hypothesis that they hibernated during that same winter.
Another interesting bit is that they have found what they claim are two ulna from a protoceratopsid. It is supposed to be very similar to, but not the same as, one from a Leptoceratops. They are close enough that they speculated that if they had been found in any part of the former Laurasia then they would have just been assigned to Leptoceratops. This would be the first report of a ceratopsian of any sort in Gondwana. The fact that it is a protoceratopsian, instead of, say, psittacosaur earlier than any known protoceratopsian...well, let's just say that's a little surprising. Twere I a professional I'd be wondering about that identification since it casts a hugely questionable light on the accepted evolution of the ceratopsians. That wouldn't be so bad - new evidence changes our perceptions of the past and evolution - except that it has a rather different than - and contradictory to! - what the fossil evidence supports to date.
(saved from a very disreputable site, if someone has a cite...)It gets stranger than that still. You see, they also found a placental mammal: Ausktribosphenos nyktos. They state that A nyktos is closely related to hedgehogs and that those are closely related to primates (which is weird: I've not heard that from any other place in my life, but bare with me). They suggest that the pre-primates actually originated in Australia (!!!) and that through a case of a microplate being shed from NorOz to drift north to Laurasia where the critters carried would go on to the evolutionary history we now know. They call it the Noah's Ark scenario.
The holes that I can see are that the hedgehogs, last I checked, were not that closely aligned with primates. Second, since the ulna found that have been tentatively identified as ceratopsian lacks a complete skeleton or even anything more than the two ulna, it seems possible this might be something else. Finally, what of psittacosaurus? That was close to being the most basal of the ceratopsians, iirc. That has only been found in Asia, which would hint that Asia is the source of the ceratopsians.
This whole scenario seems really out there, honestly. Interesting, to say the least , but really out there.
4 comments:
Fascinating summary of the book, one that I must look out for myself. It seems that this publication may ask more questions than it provides answers. I am familiar with some of the work by Dr Tom Rich and his wife Dr Pat Vickers-Rich within the Dinosaur Cove site and East Gippsland. Dinosaurs living in a polar forest would certainly strengthen the belief that many of them were warm-blooded. As for the protoceratopsian, this is a most interesting find, although the isolated ulnas are not definitive confirmation of the evolution of ceratopsians from Gondwana. Hasn't there already been a member of the ceratopsia found in Gondwana? I thought Notoceratops bonarelli from Argentina was the first to be found. If this animal is a ceratopsian it may indicate that a land bridge between South America and Laurasia existed for longer than first thought.
Great to see these subjects getting blog space, keep up the good work.
Mike Walley
http://blog.everythingdinosaur.co.uk
Notoceratops ahs been regarded as a nomen dubium, iirc. The Aussie ceratopsian has been named, it appears:
http://en.wikipedia.org/wiki/Serendipaceratops
Thanks Will,
Appreciate the update on the "southern horn face", most kind.
Mike
http:blog.everythingdinosaur.co.uk
I've met Tom Rich, the book's primary author, and Australia's leading paleontologist. He's doing more work up here in AK now, working almost every season up on the Colville River on the North Slope. He wants to burrow into a river cliff, just like he burrowed into the stones in Australia, but given that AK is heavy on the permafrost, if he did that, he'd be waist-deep in mud before long.
Tom is a very nice guy, but a little...hmm...eccentric.
I have his book, and the "Dinosaurs of Darkness" exhibit visited the AK Museum of Natural History a few summers back, where I volunteer. The traveling show should really be called "Dinosaurs and other prehistoric animals of Mongolia," because for the most part these are Mongolian dinosaurs and therapsids. Very few Australian animals. There's a Crylophosaurus skull mounted on an Allosaurus fragilis skeleton, though.
The book frustrated me because it's more about the digging and discovering and history of the site than the animals themselves. The ceratopsian hypothesis is pretty weak. The questionable ulna was shown next to a Protoceratops ulna in the exhibit, and the difference is actually fairly substantial when you really look at the two bones together.
There's some evidence of oviraptoroid material, but again, it's incredibly fragmentary. A possible allosaur will probably turn out to be an abelisaur or ceratosaur. The supposed ornithomimosaur is most likely a late-surviving coelophysoid. If Koolasuchus is any guide, then Early Cretaceous Australia was clearly as "refuge" for ancient fauna, just like it is today.
Even the mammals, which are supposedly placental, are probably marsupial and/or monotreme. The whole placental diagnosis is based on tribosphenic molars, which paleontologists are quickly finding arose several times among different mammalian lineages (actually, interesting footnote: so did the Mammalian Middle Ear!).
What's really fascinating to me is that hypsilophodonts really diversified in Australia while they were outcompeted in the rest of the world by iguanadontids and hadrosaurs.
Anyway, I think Tom Rich wants Autralia to be something really special in terms of "turning points" for the evolution of various vertebrate lineages. Placentals, oviraptors, ceratopsians. All of those hypothesis require far too much "Noah's Arking" for my tastes. There are more parsimonious explainations, and for now I'll stick with those.
Post a Comment