Researchers from Carthage College were digging in the badlands of Montana, a hotbed of paleontological research, when they came across near-perfectly preserved fossil impressions of the skull of a new type of tyrannosaur species. The team named the 75-million-year-old species Daspletosaurus horneri, or “Horner’s Frightful Lizard,” to honor the legendary paleontologist Jack Horner. The fossils were described as “excellently preserved” and have offered a rare glimpse not only at the soft tissues of a tyrannosaurid face but at a previously unknown dinosaur organ.
The fossils contained impressions of the dinosaur’s scaly skin, revealing that its face was covered in a thick armor-like plating and had no lips. The dinosaur’s armored skin continued down the snout, terminating just behind the teeth and the armor plating extended deep into the dinosaur’s facial tissues, almost to the bone.
More interestingly, these fossils have revealed that Daspletosaurus horneri (and possibly all tyrannosaurids) possessed extremely sensitive tactile organs known as integumentary sensory organs (ISOs) designed to help the quasi-armless dinosaurs investigate their surroundings. These organs ran alongside the T-Rex’s jaws and snout and could sense temperature and pressure to a high degree of sensitivity.
According to their published analysis in Scientific Reports, the researchers believe that the primary uses of this facial tactile system might have been used primarily for mating and reproduction:
[F]emale tyrannosaurids would have relied upon ISOs on the snout for detecting the optimal temperature of a nest site, and for maintaining nest temperature and the nest materials; also, ISOs would have aided adult tyrannosaurids in harmlessly picking up eggs and nestlings and, in courtship, tyrannosaurids might have rubbed their sensitive faces together as a vital part of pre-copulatory play.
Modern-day crocodiles possess similar integumentary sensory organs in their faces which function in much the same way as in these tyrannosaurids.This finding builds on previous research into the branching evolution of the trigeminal nerve in vertebrates, believed to grant some species their unique “sixth senses” such as magnetic reception in some birds and reptiles or infrared sensing in some snakes.