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RE: Why non-avian dinosaurs weren't able to survive
Many different possible answers, but at present we can't tease out which one(s)
* On land, there is a strong size bias at the K/Pg boundary. On average
non-avian dinosaurs were larger than the survivors. Was this
--smaller absolute amount of food available, so that larger endothermic
animals simply didn't have access to enough food?
--inability to hide from the thermal pulse in the minutes/hours after impact?
--inability to hide in warm spots during Impact Winter?
* Also, the larger body size but small birth size meant that non-avian
dinosaurs went through more growth stages ecologically than
most contemporaries. If any one of these turned out to be vulnerable, the
species would go extinct. (Fowler's hypothesis).
* Crocodilians fed from the freshwater ecosystem; many branches of Aves already
present fed from the marine ecosystem. Both of these
have a "pantry" in the form of bottom-feeders with access to food not as
directly tied into the immediate photosynthetic pathway. In
contrast, the sun -> plant -> herbivore -> carnivore pathway on land and its
equivalent in the pelagic realm were very strongly
affected; non-avian dinosaurs (and hesperornithines, and maybe the Late K
enantiornithines) were part of these pathways.
So there are many possible reasons.
Thomas R. Holtz, Jr.
Email: firstname.lastname@example.org Phone: 301-405-4084
Senior Lecturer, Vertebrate Paleontology
Office: Geology 4106, 8000 Regents Dr., College Park MD 20742
Dept. of Geology, University of Maryland
Faculty Director, Science & Global Change Program, College Park Scholars
Office: Centreville 1216, 4243 Valley Dr., College Park MD 20742
Mailing Address: Thomas R. Holtz, Jr.
Department of Geology
Building 237, Room 1117
8000 Regents Drive
University of Maryland
College Park, MD 20742-4211 USA
> -----Original Message-----
> From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu] On Behalf Of
> Sent: Monday, November 23, 2015 6:43 AM
> To: email@example.com; firstname.lastname@example.org; email@example.com
> Subject: Why non-avian dinosaurs weren't able to survive
> Good day,
> I would like to make myself clear about what is the actual scientific opinion
> on this question. How is it possible that very
> creatures in ecological and physiological sense, i. e. birds and crocodiles,
> survived into the Cenozoic, while non-avian dinosaurs
> not? Given that some of them were endothermic (?), cursorial, fossorial and
> equipped with a feathery integument, why they didn't
> make it into the new era? Were mammalian and bird survivors "better" in
> something, did they have more "usable"
> adaptations or were they just less specialised and more resilient? Thank you,