A study published this week shows how the tyrannosaurus consumed different resources in multiple stages of growth. Modern carnivorous mammals can easily be arranged in a graph showing the average size of an adult; each of these animals has a unique effect on its own ecosystem. Given the average size of adult dinosaurs, there seemed to be a huge gap in the middle of the graph from smallest to largest.
There is a gap in the table of adult carnivorous dinosaurs for each of the three major Mesozoic periods. The Triassic, Jurassic, and Cretaceous all have a severe lack of medium-sized “carnivorous asurians” (as Lex from Ariana Richards called them in Jurassic Park).
Why in modern times do we have carnivores in an orderly range, from small to the size of a lion, but in the time of the dinosaurs, we didn’t have them? Researchers from the University of New Mexico and the University of Nebraska proposed a new theory: Morphospecies.
ON: Fig. 3 The gap between dinosaurs and modern carnivorous mammals. (A) Kruger National Park carnivorous mammals organized at scale by mass. (B) Carnivorous dinosaurs of the Dinosaur Park Formation if the largest carnivore were scaled equally to the largest Kruger mammalian carnivore. Babies (gray) of the largest species are shown below the adult to show a relative growth requirement. IMAGE, DESCRIPTION: UNM Department of Biology.
You may have heard about the change from the old way of thinking about dinosaurs to the new, the change in recent decades that reduced the number of individual dinosaur species from many to … significantly less than previously suspected. . If you’ve never seen the TED talk with Jack Horner on “shape-shifting dinosaurs,” I suggest you take the time to do so; is one of the most viewed TED talks in the history of TED talks.
Keep this in mind as you read the rest of the article published this week by the researchers (as described above). The ancient way of thinking about each individual set of bones as a new dinosaur allowed scientists to see a much more “complete” range of dinosaur sizes, as we see with modern day carnivores. When people like Jack Horner came along, that theory was shattered.
Now, with this latest research, morphospecies theory makes sense of the broken pieces of this puzzle. We don’t see individual carnivorous dinosaurs filling all the size gaps, from small to large, because dinosaurs like T-rex were there, capitalizing on its full range of sizes as they grew from a tiny baby, just hatched from an egg, to the largest meat eater of all.
Tyrannosaurus was such an efficient carnivore that it had a significant impact on the ecosystem in which it lived at each stage of growth. Why have carnivorous mid-range dinosaurs when you could have more T-rex?
For more information, take a look at the article “The influence of young dinosaurs on community structure and diversity” published in Science. This article was written by Katlin Schroeder, S. Kathleen Lyons, and Felisa A. Smith. The research can be found under the DOI code: 10.1126 / science.abd9220 as published in Science Volume 371, issue 6532, February 26, 2021.