A study released this week shows how the tyrannosaurus consumed different sources at different growth stages. Modern carnivorous mammals can be easily arranged in a table showing the average adult size – each of these animals has a unique effect on their own ecosystem. Given the average size of adult dinosaurs, it appears that there is a large gap in the middle of the graph, from the smallest to the largest.
There is a gap in the graph of dinosaurs eating meat for each of the three main periods of the Mesozoic. The Triassic, Jurassic and Cretaceous have a severe lack of medium-sized “meat-meat asauruses” (as Ariana Richards’ Lex called it in Jurassic Park).
Why do we have carnivores in a neat range, from small to lion size, but in dinosaur times we did not? Researchers from the University of New Mexico and the University of Nebraska have proposed a new theory: Morphospecies.
ABOVE: FIG. 3 The dinosaur gap with modern carnivorous mammals. (A) Carnivorous mammals of the Kruger National Park organized by mass according to scale. (B) Carnivorous dinosaurs from the formation of the Dinosaur Park as the largest carnivore are equal to the largest mammal carnivore in Kruger. Babies (gray) of the largest species shown below have adults to show a relative growth requirement. IMAGE, DESCRIPTION: UNM Biology Department.
You may have heard of the shift in the old way of thinking about dinosaurs and the new one, the shift over the past few decades that has reduced the number of individual species of dinosaurs to … significantly less than previously thought. If you’ve never seen the TED talk with Jack Horner about ‘Shifting Dinosaurs’, I suggest you take the time to do so – it’s one of the most watched TED talks in the history of TED talks. .
Keep this in mind as you read the rest of the article published by researchers this week (as outlined above). The old way of thinking about each individual set of bones as a new dinosaur has enabled scientists to see a range of dinosaur sizes that were much more “complete”, as we see with carnivores in modernity. When people like Jack Horner showed up, the theory was shattered.
Now, with this latest research, the morphospecies theory makes sense from the crushed pieces of this puzzle. We do not see individual carnivorous dinosaurs filling every size gap from small to large, because dinosaurs like T-rex were there, utilize their entire range of sizes as they grew from a small baby, just from an egg, to the most massive carnivore of all.
Tyrannosaurus was such an effective carnivore that at each growth stage it had a significant impact on the ecosystem in which it lived. Why have giant dinosaurs with carnivores if you could just have more T-rex?
For more information, see the paper “The Influence of Youth Dinosaurs on Community Structure and Diversity” as published in Science. This article was written by Katlin Schroeder, S. Kathleen Lyons, and Felisa A. Smith. Research can be found with code DOI: 10.1126 / science.abd9220 as published in Science Volume 371, Issue 6532, 26 February 2021.