Among the largest carnivores to have ever walked over this green Earth, none were bigger than the therapods. Among them are the mighty Tyrannosaurus or Allosaurus, which lived some 65 and 150 million years ago, respectively. T. Rex was in fact, the last known member of the tyrannosaurids, before the great Cretaceous–Paleogene extinction event. Their descendants today are the many birds flying, swimming or walking all over the place.
Now, according to a recent study made by Terry Gates, a paleontologist who lectures at North Carolina State University, he discovered that there is a strong link between the huge carnivorous dinosaurs and ornamental headgear. After examining 111 therapods of different shapes and sizes, some with bony crests, horns, and knobs on their heads, and some without, Gates and his team made an interesting discovery.
After they collected all the data and put it into a computer model, the researchers found that those theropods weighing under 36 kg (80 pounds) completely lacked any kind of cranial ornamentation, while 20 out of the 22 largest theropods, had a headgear of some sort. The really interesting discovery here is that, during their course of evolution, dinosaurs with head displays made huge leaps in size every 4 to 6 million years. On average, these kinds of dinosaurs evolved to huge sizes 20 times faster than those who had no cranial ornaments
“We were surprised to find such a strong relationship between ornaments and huge body size in theropods,” Gates explains. “Something about their world clearly favored bling and big bods.”
He believes that this trend is quite significant and shouldn’t be quickly disregarded by the scientific community. Though not completely understood, scientists tend to agree that such ornaments, either of past dinosaurs or modern-day animals, like elk, serve to attract mates and fend off predators and rivals. However, there could be more to it than that.
In order to follow the thread even further, Gates and his team now study Galliformes, like chickens, turkeys, and quails, the direct descendants of some of these carnivorous dinosaurs. Judging from fossils of Velociraptor, Ornithomimus, and Falcarius, some of the direct ancestors of birds, these theropods defy the observed pattern. While over 36 kgs, these dinos did not show any signs of headgear. From an evolutionary standpoint, this can make a lot of sense, since it can be quite “costly” to have a bone headdress, it in turn needing reinforcing vertebrae for instance. Especially if these dinosaurs had feathers.
“The best explanation is that the long stiff feathers, which originated in this group of dinosaurs and were similar to modern bird feathers, could perform equally well as social signals when compared to the bony displays in T. rex or Dilophosaurus,” Gates surmises.