Byronosaurus

Byronosaurus was a small, specialised troodontid theropod that lived during the Late Cretaceous in the ancient desert landscapes of Mongolia. Measuring roughly one and a half to two metres long and weighing around fifteen kilograms, it was about the size of a large dog. Its skull was long and low, possessing delicate jaws packed with needle-like teeth that notably lacked the coarse serrations typical of many other troodontids. This dental design suggests Byronosaurus preyed on small invertebrates, lizards, and primitive mammals, or perhaps plucked eggs and soft flesh. Fossil finds include exceptionally preserved skulls and even embryonic or hatchling remains. These tiny young were found within an oviraptorid nest, prompting speculation about whether they were trophies brought back by parents or evidence of nest parasitism.

Perinatal specimens discovered inside an oviraptorid nest suggest its young were preyed upon or brood-parasitic.

Where and when

Byronosaurus lived in the Late Cretaceous, from 75 to 71 million years ago (Campanian age). Its remains come from Mongolia, in the Djadokhta Formation.

The numbers

Length 1.8 m (estimates run from 1.5 to 2 m). Mass about 15 kg. Hip height about 0.6 m. That is 1.1 human-lengths, or 0.16 of a double-decker bus. These are estimates from partial skeleton; fields marked estimated by the site are length, mass, first ma, last ma, hip height.

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