Guest Author: James Ormiston
Palaeontology MSci Graduate / Palaeoartist
Ammonites are wonderful things. Staring into their ribbed spirals can be a hypnotic experience. A shape that is vaguely familiar…yet also alien and ancient. Geometrically satisfying, chronologically dizzying. Although being very common, it’s this slight “otherness” which all but guarantees that if you collect fossils, even only a little, you probably have an ammonite in your collection. They have become a poster child for fossils worldwide.
Dinosaurs were famously stupid, but what about Theco, the Bristol dinosaur? In a new study, just published (October 2021), Bristol PhD students Antonio Ballel and Logan King, certainly don’t revise that view; there is no evidence (i’m afraid to say) that Thecodontosaurus was any more brainy (or any more stupid) than any other dinosaur of its size. However, their study does show two things: Theco held its head steady while moving, maintaining a steady gaze, and it had pretty good hearing.
The new study is based on CT scans and detailed digital reconstruction from the amazing Thecodontosaurus braincase in the collections at Yale University. In the image, you can see the braincase (top left), the reconstructed key bones (top right) and images showing the semi-circular canals, highlighted in pink (bottom left and right).
The steady gaze evidence comes from bumps on the side of the Theco brain called flocculi: in modern animals these assist the animals in keeping their head steady as they run and duck and dive, using two responses – one to keep the eyes fixed on any object in their field of view, and the other to keep the head steady. This new finding confirms that Thecodontosaurus was adept at moving bipedally, on its hind legs, and the fixed gaze adaptations would have helped it if it occasionally hunted prey. We’ve always said Theco was a herbivore, and it primarily was, but many early dinosaurs seem to have mixed and matched, and would have grabbed a juicy beetle or small lizard if they had a chance.
It might also seem amazing to be able to estimate the hearing ability of a dinosaur. This can be done using standard formulas based on measuring parts of the braincase and cochlear duct buried in the bone of the skull. It was specialized to hear low and middle frequencies of sounds, similar to other dinosaurs and early birds. These sounds could have included chirping and grunting from other Thecos, and so provides some evidence for group living and some social behaviour where they chattered to each other.
News story here and the new paper is here.
With Halloween only two days away, I thought we should turn our attentions to an animal which has become synonymous with the holiday. The word ‘Halloween’ conjures up a series of distinctive shapes in our minds; a pumpkin, a ghost, the far too early Christmas tree in the shops, and the silhouette of a flying bat. But how long could it have been this way? Would a bat have been a symbol of Halloween in the Mesozoic (if dinosaurs had been capable of celebrating this autumnal festival or been dextrous enough to craft decorations to mark it)?
Everyone knows about the great extinction at the end of the dinosaur age, but it was far from smooth sailing up until then. The Mesozoic era stretches out 180 million years, during which time many different groups of animals exploded into abundance and then died away. Even without anything so dramatic as an asteroid impact much of these were still significant catastrophes. One such time is the Toarcian Oceanic Anoxic Event (T-OAE). (more…)