The empire of the senses of the dinosaurs

NOTe other species of euarchontoglires – a group that includes placental mammals – perceive the world in our own way. But what about the dinosaurs, masters of the emerged lands between 240 and 66 million years ago, swept away (apart from the birds) by a Schumpeterian meteorite? This is what Jean Le Loeuff invites us to discover, in a book that immerses us in “In the skin of a dinosaur”.

The paleontologist, director of the Espéraza Dinosaur Museum, in Aude, relies for this on the most recent scientific literature. His tone, however, has nothing academic about it, finding the right distance between erudition and banter.

To try to resuscitate the perceptual apparatus of dinosaurs, the most relevant is first to describe their brain. But the borders of it, whether we make molds of it or scan it with X-rays, are blurred by the brains that surround it, like a pie: “The thicker the crust, the less detail there will be about the shape of the pâté inside”, warns Jean Le Loeuff. It’s a shame, but that does not prevent us from wondering about their intellectual performance and from attempting comparisons with crocodiles and birds, their closest cousins. The encephalization quotient places small carnivorous dinosaurs at the pinnacle of “dinosaur brains”.

The methanized emission of the dinosaurian fart

Steven Spielberg was wrong to portray his tyrannosaurus rex decked out “of the olfactory capacities of a Covid patient”rectifies the paleontologist: the heroes of Jurassic Park would not have escaped his olfactory bulbs. These animals themselves had to produce and why not communicate through smells – like the caiman whose paracloacal glands diffuse a fragrance of… lemongrass. This chapter evokes in the same movement the dinosaurian fart, whose methanized emission could have contributed to the warming of the Mesozoic climate.

The vision also reveals its share of surprises. The Velociraptor – “a real ringworm” – seemed to be particularly well endowed, with its large binocular eyes, the semicircular canals of the inner ear and the cerebral flocculus coordinating vision and movement. The inner ear, again, accessible to the CT-Scan, also betrays the auditory faculties of our critters, which seem adapted to the capacities of some of them to emit sounds. A link to an augmented reality application even allows you to listen to the song of the parasaurolophus at the bottom of the woods. At the very beginning, recalls Jean Le Loeuff, in the absence of birds, frogs, mammals and insects, the soundscape of the Triassic had to be “relatively grim”.

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