What a week it's been for palaeontology in the news, especially related to taphonomy! There's a new paper on the taphonomy of the Cleveland-Llyod Dinosaur Quarry, a paper describing featherless patches of skin on Tyrannosaurus rex, and now a mid-Cretaceous 'bird' (avialan) hatchling has been found encased in Burmese amber!
Photograph of the amber specimen with a hatchling enantiornithine preserved within (a), with combined x-ray and micro-CT scan (b), and illustration of body outline and position (c). Figure from Xing et al., 2017.
The hatchling is from a now-extinct group of avialans called enantiornithines. It is a 'bird' in the broadest sense, but just not from the same lineage that modern-day birds belong to (the neornithes).
The preservation of this specimen is fantastic. The right foot is clearly visible with the podotheca, claw sheathes, and feathers still intact. More difficult to see is the head and neck of this hatchling, but with the help of micro-CT and x-ray, Xing et al. (2017) show that they are present and also well preserved.
How did this hatchling end up in a lump of amber? Amber is preserved tree sap or resin, and while tiny animals such as insects are normally the victims of sticky-sap entrapment, small vertebrates such as frogs, lizards, and (as described by the same authors in a previous paper) a small dinosaur or bird tail have also been known to get caught in ancient resin. As for this hatchling, the authors propose that only part of the body was covered in resin (either during or soon after death), with the rest of the body remaining uncovered and exposed to the elements. Later, a second resin flow covered the remainder of the body.
The preservation of this specimen is fantastic. The right foot is clearly visible with the podotheca, claw sheathes, and feathers still intact. More difficult to see is the head and neck of this hatchling, but with the help of micro-CT and x-ray, Xing et al. (2017) show that they are present and also well preserved.
How did this hatchling end up in a lump of amber? Amber is preserved tree sap or resin, and while tiny animals such as insects are normally the victims of sticky-sap entrapment, small vertebrates such as frogs, lizards, and (as described by the same authors in a previous paper) a small dinosaur or bird tail have also been known to get caught in ancient resin. As for this hatchling, the authors propose that only part of the body was covered in resin (either during or soon after death), with the rest of the body remaining uncovered and exposed to the elements. Later, a second resin flow covered the remainder of the body.
References
Xing, L., O'Connor, J. K., McKellar, R. C., Chiappe, L. M., Tseng, K., Li, G., Bai, M., 2017. A mid-Cretaceous enantiornithine (Aves) hatchling preserved in Burmese amber with unusual plumage. doi: 10.1016/ j.gr.2017.06.001
