After-All-Yesterdays

A new study has looked into the jaws of placoderms and concluded: That there were extensive cartilage and other soft tissues not previously detected That, unlike modern fish, they likely weren’t capable of extending their jaws for suction feeding. The former is interesting given that there’s a hypothesis that placoderms had lips. The study concludes muscular lips are unlikely as they’re exclusive to mammals, but doesn’t rule out the soft tissue detected forming minor covering. The second is interesting because the jaws of acanthodians and early ray-finned fish are more bulky and seem more attached to the skull bones than those of modern fish (cartilaginous and osseous both), which suggests more flexible and expansive jaws evolved independently. Overall this is a great look into the evolution of the vertebrate jaw and a firmer understanding of placoderms.

A new study has examined the phylogenetic relationships of Unenlagiinae, recovering them as closer to birds than to dromaeosaurs as previously thought. The same study also recovers halszkaraptorines as sister taxa to unenlagiines, positing a possible origin of the group in Asia. The paper notes that at least two unenlagiines, Rahonavis and Buitreraptor, are capable of powered flight. They are rather ambivalent if flight originated a single time in Maniraptora or if it evolved multiple times, but they lean more towards the former option given the energy expenditure required for multiple origins of flight. The study does recover the volant scansoriopterygids as sister taxa to oviraptors, and in the case of the latter Caudipteryx is apparently secondarily flightless, so an origin of flight deep within Coelurosauria is possible (as Mickey Mortimer notes, Pelecanimimus has “flighty” characteristics). Adaptation for flight may also explain the robustness of halszkaraptorine wings despiste