Dinosaur vs. Mammal: Dawn of Justice

July 18, 2023 11:39 PM

An extraordinary fossil captures the struggle for existence during the Mesozoic.

Dinosaurs and mammals have coexisted for the last ~ 230 million years. Both groups arose during the Late Triassic and diversified throughout the Mesozoic and into the Cenozoic (the latter in the form of birds). Although they undoubtedly interacted in many ways, direct fossil evidence for their interaction is rare. Here we report a new fossil find from the Lujiatun Member of the Lower Cretaceous Yixian Formation of China, showing a gobiconodontid mammal and psittacosaurid dinosaur locked in mortal combat. We entertain various hypothesized explanations for this association, but the balance of the evidence suggests that it represents a predation attempt on the part of the smaller mammal, suddenly interrupted by, and preserved within, a lahar-type volcanic debris flow. Mesozoic mammals are usually depicted as having lived in the shadows of their larger dinosaurian contemporaries, but this new fossil convincingly demonstrates that mammals could pose a threat even to near fully-grown dinosaurs. The Yixian Formation—and the Chinese fossil Jehol Biota more broadly—have played a particularly important role in revealing the diversity of small-bodied dinosaurs and other fauna. We anticipate that the volcanically derived obrution deposits specific to the Lujiatun Member will likewise continue to yield evidence for biotic interactions otherwise unknown from the rest of the fossil record.

posted by brundlefly (12 comments total)

I think I vote for the scavenging scenario.

The three counter arguments are: no bite marks on the bones (but maybe the mammal just hadn’t got that deep yet), entanglement (but I reckon scavengers do get really entangled with what they’re eating) and the mammal was on top instead of just eating the dino from the side (getting on top seems natural to me - would a jackal never climb on to a dead ungulate?)

But who knows? Very interesting.
posted by Phanx at 1:01 AM on July 19, 2023

This also reminds me of one of the greatest fossil finds of all time.
posted by brundlefly at 2:02 AM on July 19, 2023 [2 favorites]

MetaFilter: the mammal was clearly the aggressor in the preserved interaction.

--

I see that they acknowledge that there have been forged fossils in the past, but feel this one is legit. I don't think a curator would dare imagine creating a scene so amazingly full of life as this.
posted by wenestvedt at 7:24 AM on July 19, 2023

Weird use of the word justice.
posted by metametamind at 7:41 AM on July 19, 2023

I’m happy to see that my ancestor, the mammal, had the same kind of bones as me in its forearm and hand, way back then. Nice to feel connected to the deep past.
posted by njohnson23 at 8:02 AM on July 19, 2023 [2 favorites]

eating of still-living pretty by African wild dogs is conceivably one such adaptation.

I bet this is some autocorrect typo but it has quite a ring to it.
posted by foxfirefey at 8:15 AM on July 19, 2023

Nice to know scenes like this have been playing out for 126 million years:

https://www.youtube.com/watch?v=5sAF8gMN9c0
posted by Schmucko at 8:34 AM on July 19, 2023

Well I need to go tell all my friends.

a gobiconodontid mammal and psittacosaurid dinosaur locked in mortal combat

TEST YOUR MIGHT
posted by justsomebodythatyouusedtoknow at 8:49 AM on July 19, 2023 [2 favorites]

Weird use of the word justice.

I assume the poster was referencing this movie title.
posted by Greg_Ace at 9:03 AM on July 19, 2023

Maybe they were just hugging
posted by gottabefunky at 9:08 AM on July 19, 2023 [2 favorites]

That is correct, Greg_Ace. Half of my life is spent making doofy jokes in a film dork slack group, and I forget that not everyone is on that page.
posted by brundlefly at 11:03 AM on July 19, 2023 [2 favorites]

Maybe they were just hugging

After finding out both of their mums were named Martha
posted by nubs at 3:00 AM on July 20, 2023 [1 favorite]