Allosaurus jimmadseni Chure & Loewen, 2020

While Allosaurus jimmadseni was named much more recently than Allosaurus fragilis, it lived a bit further ago in time, in the lower Morrison Formation of the American West. It’s possible that A. jimmadseni evolved into A. fragilis, although direct ancestor-descendant relationships are difficult to test.

Here we have two individuals at very different growth stages, so this page gathers them as a small hub — a subadult and a juvenile drawn to scale. Check out the size comparison, or pick a specimen below to see its own reconstruction and record; an adult specimen is in progress, and will eventually join the others here.