Dinosaur News #20

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Deviation Actions

Albertonykus's avatar
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New dinosaurs include hadrosaur (duck-billed dinosaur) Acristavus gagslarsoni, archaeopterygid (Archaeopteryx lithographica and kin) Xiaotingia zhengi, oviraptorosaurs (box-headed dinosaurs) Ojoraptorsaurus boerei and Epichirostenotes curriei, and an indeterminate carcharodontosaurid (shark dinosaur).

The phylogenetic analysis in the description of Xiaotingia zhengi finds Anchiornis huxleyi to be an archaeopterygid and archaeopterygids to be deinonychosaurs ("raptors"). Australodocus bohetii is found to be a titanosauriform and Camposaurus arizonensis is found to be a neotheropod related to Megapnosaurus rhodesiensis. A study on how sphenisciforms (penguins) jump out of the water is published.
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SpongeBobFossilPants's avatar
Y'know, it's funny. Back when Paul wrote Predatory Dinosaurs of the World, he considered his placement of Archaeopteryx as a deinonychosaur as "by far the most radical" of his reclassifications. Looking back on the book from a 21st century perspective, it's one of his more plausible ones.
Albertonykus's avatar
SpongeBobFossilPants's avatar
What do you make of Mickey Mortimer's suggestion that Epichirostenotes really is Chirostenotes?
Albertonykus's avatar
It's certainly possible. His main point is that it essentially can't be compared anatomy-wise with known Chirostenotes material. We'll see really.
SpongeBobFossilPants's avatar
If they've narrowed it down to Carcharodontosauridae, how indeterminate can it be?
Albertonykus's avatar
As in too fragmentary to actually name (in the authors' opinion).
SpongeBobFossilPants's avatar
"The phylogenetic analysis in the description of Xiaotingia zhengi finds Anchiornis huxleyi to be an archaeopterygid and archaeopterygids to be deinonychosaurs ('raptors'). "

Cool. So are they their own family, or do they fall in Dromaeosauridae or Troodontidae, or what?

Not to mention, I was skeptical of the archaeopterygids' avialain status recently. Personally, I suspected that they were the common ancestors of the deinonychosaurs and avialains.

Just wait until Xiaotingia turns out to be a different type of maniraptoran...
Albertonykus's avatar
They're non-dromaeosaurid, non-troodont deinonychosaurs (their own group, in other words). Also, the description of Samrukia has Archaeopteryx as a basal paravian.
SpongeBobFossilPants's avatar
Say, if archies are deinonychosaurs, would that prove Oviraptorosauria & Avialae to be sister groups?
Albertonykus's avatar
Avialians by definition are closer to modern birds than to Deinonychus, so archies wouldn't be avialians at all in that case. Aves sensu lato would expand to encompass deinonychosaurs however (as Archaeopteryx is a qualifier for Aves sensu lato), but even then Aves and Oviraptorosauria wouldn't be sister groups because there's the possibility of there being non-avian paravians.
SpongeBobFossilPants's avatar
That's not really what I meant. I read an article saying that, based on the similarity between oviraptorosaur & basal avialian skulls, those two would be sister groups if archies are deinonychosaurs.

P. S. I added another post to the current bad dinosaur book topic.
Albertonykus's avatar
Archies being deinonychosaurs alone would not influence that at all. The most recent paper finding Archaeopteryx to be a deinonychosaur (the Xiaotingia paper) does not also support that result, for instance. In this case all the similarity between basal avialians and oviraptorosaurs skulls probably means is that blunt skulls are basal for aviremigians, with deinonychosaurs evolving pointy skulls once.

Gregory Paul has suggested that omnivoropterygids might be basal flying oviraptorosaurs, but... that's Greg Paul, and even then that topology doesn't mean oviraptorosaurs and avialians become sister groups. More tellingly, there have been hints that something similar might be coming up in actual technical literature sometime in the future...
SpongeBobFossilPants's avatar
Handy bit of Fridge Brilliance: If Oviraptorosauria is closer to Passer than to Deinonychosauria, wouldn't that make oviraptorosaurs avialians?
SpongeBobFossilPants's avatar
"The most recent paper finding Archaeopteryx to be a deinonychosaur"

You mean there have been others?
Albertonykus's avatar
I don't know about others that have recovered it as a deinonychosaur specifically, but this isn't the first time it's turned up as a non avialian. (Off the top of my head, so does the Gigantoraptor description paper.)
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SpongeBobFossilPants's avatar
Similar to Paul's suggestion, you mean?
Albertonykus's avatar
All we know is that it involves omnivoropterygids and oviraptorosaurs. We'll see.
SpongeBobFossilPants's avatar
Cool. And about Camposaurus... Wasn't it always a member of Coelophysidae?
Albertonykus's avatar
Yes, although it's been considered dubious. This study took an in depth look at its relationships and whether it's diagnostic.
Algoroth's avatar
How much of Australodocus have they found?
Albertonykus's avatar
I think it's only known from a couple of neck vertebrae, but I'm not that up to date with sauropods.
Algoroth's avatar
I was hoping for more info. It might have helped with a current project. Thanks! :)
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