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Now that - FINALLY- I'm done with the 'Too Many Damn #Dinosaurs' (TMDD!) series at #TetZoo (in which I talk about claims that there are just too many sauropods in the #MorrisonFormation), I'm going to (slowly) produce a thread which goes through the arguments...
For as long as I've been interested in #dinosaurs, I've been aware of arguments positing that 'there are too many taxa' (especially among big species), and that having more than 2 or 3 species in the same area or geological unit is problematic from an ecological point of view...
This view was promoted most recently by Don Prothero in a blog article and book. Inspired by the 2015 resurrection of #Brontosaurus, he suggested that Morrison Fm diplodocid taxa are likely over-split and that experts need to check this possibility... cont..
Of course, Prothero's argument doesn't make sense, since the resurrection of a genus (viz, a taxonomic decision) doesn't tell you anything about diversity and ecology - the _species_ would stand, whatever genus it was placed in.
Furthermore, sauropod experts have checked and checked again the possibility that these animals might need to be synonymised, or recognised as growth stages... and evidence convincingly shows that they're mostly distinct taxa.
A separate argument is that certain Morrison Formation sauropods might be regarded as growth phases of others, in which case 'extreme ontogeny' might have happened. This has been contested and doesn't look valid. It's inspired by the Nanotyrannus, Dracorex & Torosaurus debates.
I set out the 'Too Many Damn Dinosaurs!' contention in this #TetZoo article, Part 1 in the series ... http://tetzoo.com/blog/2020/4/17/stop-saying-that-there-are-too-many-sauropod-dinosaurs-part-1 #dinosaurs
A key part of Prothero's argument is that 'fossil megamammals have proved oversplit, thus Morrison sauropods are too'. To do justice to this argument I had to discuss brontothere and indricothere taxonomy...
The taxonomy of these mammals is NOT directly comparable to that of Morrison #sauropods, in part because the over-split nature of the relevant taxa was long known to be problematic, and was resolved as soon as it was properly studied. Here's the article: http://tetzoo.com/blog/2020/4/19/stop-saying-that-there-are-too-many-sauropod-dinosaurs-part-2
In any case, the mammals which Prothero pointed to are not 'standalones', but clusters of species (yes, even Paraceratherium). In fact Don Prothero's 2019 dinosaur book says stuff which contradicts his 2013 book on Paraceratherium... #fossilmammals
Modern #mammals were involved in Prothero's argument too - in particular #giraffes. The reasons for this are complex and the easiest thing to do is point you to the #TetZoo article... http://tetzoo.com/blog/2020/4/21/stop-saying-that-there-are-too-many-sauropod-dinosaurs-part-3
Suffice to say that osteological variation within extant megamammal taxa - even those now suspected to be species complex (like extant Giraffa) - is subtle and not like the significant variation seen in the Morrison #sauropods Prothero compared them with. Ok, moving on...
The most erroneous angle of the TMDD contention is the inference that Morrison #sauropods were mostly contemporaneous. Prothero stated that you might find 7 or 8 “species of huge sauropods from a single interval of time and a single place, all crowding together” .... cont
But these animals were actually living across at least 7 million years and a vast geographic area, and mostly weren't found alongside one another ... http://tetzoo.com/blog/2020/4/24/stop-saying-that-there-are-too-many-sauropod-dinosaurs-part-4 #dinosaurs
Part 4 in the series also covered the taxonomic aspect of this debate. It's wrong to criticise Tschopp et al. for being 'trigger happy' with generic names (as Prothero did), seeing as they didn't just resurrect Brontosaurus, they also sank Eobrontosaurus and Elosaurus...
The TMDD contention also has it that there is no way the habitats concerned could handle the HUGE populations of these #dinosaurs that would have existed. But this makes a ton of assumptions about population size, all of which are probably nonsense ... http://tetzoo.com/blog/2020/5/1/stop-saying-that-there-are-too-many-sauropod-dinosaurs-part-5
I never finished this thread, there's still more to come. Aiming to finish it later today, stay tuned. Comments are still appearing in the last part of the series (Part 8) ... http://tetzoo.com/blog/2020/5/20/stop-saying-that-there-are-too-many-sauropod-dinosaurs-part-8-the-last-part
