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Re: [dinosaur] Dinosaurs most likely to survive the K-Pg extinction

It has been noted that the only dinosaurs that survived were derived neoornithes that brooded their unburied eggs which may have allowed the eggs to survive the strong temperature fluctuations. And all those birds had toothless bills on highly kinetic skulls that may have made them generalists able to grub up food in bad circumstances. 


-----Original Message-----
From: Thomas Richard Holtz <tholtz@umd.edu>
To: Mike Taylor <sauropoda@gmail.com>
Cc: Poekilopleuron <dinosaurtom2015@seznam.cz>; DML <dinosaur-l@usc.edu>
Sent: Thu, Aug 13, 2020 8:10 am
Subject: Re: [dinosaur] Dinosaurs most likely to survive the K-Pg extinction

I strongly disagree with Mike on this, though. Not the luck part, which is a big factor, but on the lack of a pattern.

In the terrestrial pattern the size pattern is extraordinarily strong. Animals >5 kg simply did not survive. Even within turtles and crocodilians this is true: large crocs and large tortoise mimics (such as xinjiangchelyids) did not make it.

Within the marine realm planktonic taxa and animals that fed more directly on the plankton die off at rates higher than bottom-feeding benthic organisms. Large pelagic forms die off at rates higher than small demersal forms. And so on.

That said, once you are past these filters who lived and who died among the rest seems to be more stochastic. So why Aves and not Enantiornithes? Why some mammal clades and not others? These are less certain, and probably does have a lot to do about luck.

On Thu, Aug 13, 2020 at 6:57 AM Mike Taylor <sauropoda@gmail.com> wrote:
The thing about the K-T extinction is that there is no real pattern to
what did and did not survive. Lots of indicators have been proposed:
land vs. water-dwelling, large vs. small, endothermic vs. ectothermic,
etc. But none of them fits the data, which suggests that the strongest
factor affecting survival was sheer dumb luck.

So it's not really possible to answer your question of which dinosaurs
were most likely to survive that event, beyond the obvious observation
that birds evidently did (as you noticed). It could just as easily
have been hadrosaurs or titanosaurs; and the surviving mammals could
easily have not included the lineage that led to us.

-- Mike.

On Thu, 13 Aug 2020 at 08:45, Poekilopleuron <dinosaurtom2015@seznam.cz> wrote:
> Good day to all listmembers! I would like to ask, which non-avian dinosaur species from the terminal Cretaceous are (according to you) most likely to survive the extinction 66 million years ago? Small bird like species? Specialised aquatic or burrowing forms? Are there any hints of favourable adaptations for the possible survival in the fossil record? Thank you for your opinions! Tom

Thomas R. Holtz, Jr.
Email: tholtz@umd.edu         Phone: 301-405-4084
Principal Lecturer, Vertebrate Paleontology
Office: Geology 4106, 8000 Regents Dr., College Park MD 20742
Dept. of Geology, University of Maryland
Phone: 301-405-6965
Fax: 301-314-9661              

Faculty Director, Science & Global Change Program, College Park Scholars
Office: Centreville 1216, 4243 Valley Dr., College Park MD 20742
Fax: 301-314-9843

Mailing Address:        Thomas R. Holtz, Jr.
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