[Rockhounds] Stupendously Preserved Fossil Shows Mammal Preying on Beaked Dinosaur

[Kreigh Tomaszewski]

About 125 million years ago, a young mammal about the size of a possum bit
down on the side of a beaked dinosaur nearly three times its size. The
animals died like that, entangled and at odds with each other, a fossilized
tableau of the dinosaurian-mammalian power shift that would finally come
about 60 million years later.

Those are the certainties of the Cretaceous Period exchange that
were encased in time until this week, when a team of paleontologists
revealed the stunning fossil in a paper published
<https://www.nature.com/articles/s41598-023-37545-8> in Scientific Reports.

The ancient creatures were a *Repenomamus robustus*, a carnivorous mammal,
and a *Psittacosaurus lujiatunensis*, a beaked, bipedal dinosaur that looks
like a cross between a parrot and a lizard (that’s literally what it’s name
means, too). The *R. robustus *is nearly complete, just missing the tip of
its tail, and is 18.39 inches (46.7 cm) long. The *Psittacosaurus *is 47.1
inches (119.6cm) long.

“Almost without exception, dinosaurs were larger than mammals,” Jordan
Mallon, a paleobiologist at the Canadian Museum of Nature in Ottawa and
co-author of the study, told Gizmodo in an email. “The working assumption
has therefore been that dinosaur-mammal interactions were one-way, which is
to say that the larger dinosaurs always ate the smaller mammals.”

“This new fossil reveals that these ancient food webs were a little more
complete than we might have otherwise assumed, and that mammals were
occasionally capable of eating even near fully grown dinosaurs,” he added.

https://gizmodo.com/preserved-fossil-mammal-preying-beaked-dinosaur-1850664541