【古生物学】草や葉だけが餌ではなかった草食恐竜

A group of large, herbivorous dinosaurs may not have been strict plant-eaters as previously thought, according to a study in Scientific Reports. The study suggests that some herbivorous dinosaurs may have eaten crustaceans at times during the year.

Large, plant-eating dinosaurs are usually presumed to have been strictly herbivorous, based on analyses of their teeth and jaws, which suggest they were capable of processing fibrous plant foods. Indeed, most reconstructions of the feeding behaviours of large ornithischians (a group of herbivorous dinosaurs) have been based on mammalian megaherbivores, which are regarded as body-size analogues. However, specific information about ornithischian food choices is scant.

Karen Chin and colleagues describe fossilized faeces (coprolites) from the Kaiparowits Formation in southern Utah that suggest the recurring consumption of crustaceans and rotten wood by large, Late Cretaceous dinosaurs. The large size and woody contents of the Kaiparowits coprolites suggest that the faecal masses were produced by large herbivorous dinosaurs with dentition that could process fibrous diets. However, the presence of crustacean shell-like material scattered within the coprolite contents suggest that these dinosaurs consumed sizeable crustaceans sheltered in rotting logs. The authors suspect that, based on previous finds from this formation, hadrosaurs may have produced the faecal masses.

The authors suggest that the presence of crustaceans in multiple coprolites represent a regular, perhaps seasonal, feeding strategy, which is more consistent with the diets of birds than the strict herbivore diets of most mammalian megaherbivores. The authors argue that the findings challenge simplistic interpretations of feeding habits of megaherbivorous dinosaurs.