Enantiarmithines

At https://phys.org/print461316344.html … fossil birds of the Cretaceous. We don't usually hear much about birds in the dinosaur era – not the size of crows or magpies (or even the size of turkeys). It seems there were several different kind of birds at large in the dinosaur era – but only one type of bird turns up after the K/T boundary event. The fossils in question come from a famous dinosaur site in Utah, in the Grand Staircase-Escalante area. However, what we have are the enantiarmithines. These were aerodynamic and great fliers we are told – but did not survive, unlike modern birds. I suppose it is all about filling niches in the aftermath of a catastrophic event but the press release makes a lot of the mystery of their disappearance (along with the dinosaurs). For some reason they did not fly away and escape the mayhem of the asteroid strike – but disappear from the fossil record. The wishbone of the enantiarmithines was flexible and able to drive energy during the wing stroke. The dinosaur period bone bed contained dinosaurs, crocodiles, alligators, turtles and fish – as well as these birds. Neither were the fossils smashed as in other bone beds but are preserved whole (but without feathers or soft tissue). In fact, the article seems to suggest that soft tissue is a feature of bone beds where the fossils have been flattened or smashed into pieces. Do we have a clue here on the survival of soft tissue?