Hailed as a “mini-Godzilla”, although frankly I can’t see the resemblance (sorry Hector Munive)… this enigmaatic, tiny, newest of dinosaurs has been assigned to Thyreophora, and reconstructed as a close relative of Scutellosaurus, Scelidosaurus and sundry stegosaurs and ankylosaurs. It would be the first-ever obligatory bipedal armoured dinosaur with arms as puny in proportion as those of a theropodian Abelisaurid.

Problem is: First of all it is too fragmentary. There’s a lot of guess work here. We cannot be as certain as we would like of the distribution of the armour, in a case that reminds me of Acantholipan and its bogus spines on the hips. Second, the mandible is deep and, according to Thom Holtz, closely resembles ceratopsids… something that would make Jakapil a Marginocephalian, not a Thyreophoran. Third, to reconstruct it as a scelidosaur it would be an incredibly late, Cretaceous surviving relative of the Triassic/Early Jurassic Scutellosaurus or Scelidosaurus… and a running bipedal ankylosaur is unknown to say the least. The evolutionary trend in the evolution of Thyreophora has been in getting bigger and heavier, not towards slim runners.

So. is it a really completely different branch of Ornithischian armoured dinosaur? Or is it a ‘missing link’ marginocephalian as I propose here?

I have dared to reconstruct it in a different view… here Jakapil is really a primitive armoured marginocephalian between pachycephalosaurs and ceratopsians… we do not have the top of the skull, so it might be possible that it was as armoured as the rest of the body.

It would be the first armoured pachycephalosaur for sure. An almos perfect ancestor to the rest of pahycephalosaurs linked to the ceratopsians (but also linked to Thyreophorans somehow) via a characteristic different mandible. A puzzle. A fascinating missing link! More of the skeleton is needed to reach more conclusions. Hypothetical primitive bristles paired with the armour? Why not? The rest of the animal is almost as hypothetical at this stage.

Paper is here: https://www.nature.com/articles/s41598-022-15535-6