| Speculative biology is simultaneously a science and form of art in which one speculates on the possibilities of life and evolution. What could the world look like if dinosaurs had never gone extinct? What could alien lifeforms look like? What kinds of plants and animals might exist in the far future? These questions and more are tackled by speculative biologists, and the Speculative Evolution welcomes all relevant ideas, inquiries, and world-building projects alike. With a member base comprising users from across the world, our community is the largest and longest-running place of gathering for speculative biologists on the web. While unregistered users are able to browse the forum on a basic level, registering an account provides additional forum access not visible to guests as well as the ability to join in discussions and contribute yourself! Registration is free and instantaneous. Join our community today! |
| Late Cretaceous dinosaur diversity in America | |
|---|---|
| Topic Started: May 29 2009, 05:57 AM (358 Views) | |
| Carlos | May 29 2009, 05:57 AM Post #1 |
|
Adveho in me Lucifero
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]()
|
I'm mainly discussing America because other parts of the wrld have few Maastrichian rocks, but plenty of fossil sites date from earlier in the late Cretaceous. It interesting to note how low dinosaur diversity was at the very end of the Cretaceous in North America. For example, there is only one known big predator (Tyrannosaurus), and hadrosaur, ceratopsid and ankylosaur genera was lower in number than on the Campanian and older periods of the late Cretaceous. Though there were some other clades that had more luck; the Maastrichian is noted for the presence of a North American sauropod and several of ornithomimids, plus the presence of possible therizinosaur remains as well as of small ornithopods (which, since they were absent from Laurasia for quite some time, must had been of south american origin) and some oviraptors (I don't know whereas big oviraptors like Hagryphus were still present at the very end, but small, galliforme like ones like Avimimus certainly were). Compare the several species of tyrannosaur in the Campanian with the single one in Maastrichain's North America; note that Tyrannosaurus was quite bigger than the rest, and because dinosaurs, like modern non-Neoaves archosaurs (crocodiles, ratites and fowl) tended to have precocial young most predator niches at the time could simply had been occupied by the single giant predator T-rex was, which likely grew very slowly. Arguably, the success of T-rex at occupying several niches through the lifetime probably pushed all other predators aside, as even dromeosaurs were mostly reduced to beaver-sized species at the very end of the Mesozoic. However, I don't know if this can be applied to ornithicians, as hadrosaurs had parental care, as since most theropods were precocial it probably doesn't explain how several theropods managed to co-exist in previous eras. Probably a minor extinction event occured in America. Your thoughts? |
|
Lemuria: http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/ Terra Alternativa: http://s1.zetaboards.com/Conceptual_Evolution/forum/460637/ My Patreon: https://www.patreon.com/Carliro ![]() | |
![]() |
|
| Venatosaurus | May 29 2009, 08:55 AM Post #2 |
|
HAUS OF SPEC
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]()
|
Well, I believe most theropods helped raise their young possibly forming small packs. |
|
| |
![]() |
|
| Carlos | May 29 2009, 09:36 AM Post #3 |
|
Adveho in me Lucifero
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]()
|
But there is evidence to suggest they were highly precocial. Phylogenetic evidence, for example (both crocodilians, pterosaurs and basal birds have highly precocial young, so logically theropods would have precocial young as well, even if they would be protected for a period of time). Of course, they could had developed parental care independently |
|
Lemuria: http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/ Terra Alternativa: http://s1.zetaboards.com/Conceptual_Evolution/forum/460637/ My Patreon: https://www.patreon.com/Carliro ![]() | |
![]() |
|
| 1 user reading this topic (1 Guest and 0 Anonymous) | |
| « Previous Topic · Science Central · Next Topic » |







3:32 AM Jul 11