An unusually large bird wing in mid-Cretaceous Burmese amber (1 Viewer)

[Fred Ruhe]

Lida Xing, Ryan C. McKellar & Jingmai K. O'Connor, in press

An unusually large bird wing in mid-Cretaceous Burmese amber

Cretaceous Research Article 104412 (advance online publication)
doi: https://doi.org/10.1016/j.cretres.2020.104412
https://www.sciencedirect.com/science/article/pii/S0195667119304598

Abstract: https://www.sciencedirect.com/science/article/pii/S0195667119304598

All of the bird specimens previously recovered from Burmese amber have belonged to either immature specimens, or small-bodied taxa belonging to Enantiornithes. This has led to questions about whether the size bias inherent to preservation in amber has limited inclusions to smaller individuals or species, or if the avifauna of the amber-producing forest had a stronger representation of small-bodied taxa than other Cretaceous assemblages. A newly discovered inclusion of a fragmentary bird wing is described here: specimen LV-0321 likely belonged to an individual that was in excess of 10 cm long (snout to vent length). The new specimen also displays more prominent light-and-dark banding patterns among the primary flight feathers than any of the wings previously described from the deposit. In addition to increasing the known size range for enantiornithines within the assemblage, the new specimen sheds further light on the appearance of the plumage in these Cretaceous birds.

Enjoy,

Fred

 

[jurek]

I find it interesting that in modern times, birds get caught in tree resin either never or so rarely that I cannot recall a written comment.

 

[Fred Ruhe]

I find it interesting that in modern times, birds get caught in tree resin either never or so rarely that I cannot recall a written comment.

Neither can I. But in the Cretaceous there are several cases known, almost all concerning nestlings or juvenile birds. If you want to know of these cases surch this subforum for amber and you will find several cases, but these birds were not able to fly yet, The authors write: "Burmese amber has provided a surprisingly abundant and diverse 31 suite of enantiornithine inclusions over the last five years. This material has included isolated wing fragments from uveniles, the skin and bones from the right side of a hatchling, and a more complete but strongly compressed juvenile skeleton."

It seems that only Enantiornithes that were not yet able to fly were caught in tree resin. This might have to do with the way they nested, but I don't know that.

Fred

 

[Fred Ruhe]

Fig. 1. Plumage and taphonomy of LV-0321 dorsal surface

(A) Specimen overview. (B) Detail of specimen base and pigment distribution in primaries
(C) Detail of truncated base of wing, indicating taphonomy. (D) Illustration of feather positions and taphonomic areas. (E) Detail of ungual and plumage surrounding phalanx. (F) Dorsal surface of P6, showing pigment distribution and barbule morphology. Abbreviations: ); dec, decay product mass of milky amber (pale grey in D); min, mineral infill within zone of soft tissue (dark grey in D); P1–P9, primary feather numbers; ph/am, transverse section through basalmost phalanx or alular metacarpal (white in D); plu, plumulaceous feathers on underside of wing (striated in D)

Fred

 

[jurek]

It is interesting because enantiornithes are said to fly almost directly after hatching and grow very slowly to adult size. So there should not be much flightless stage? Possibly they were flightless for a short time and scrambled over branches using the wing claws and feet in the manner of squirrels. It would be interesting whether and how much parental care they received. No modern bird is altricial and has tree-living chicks.

 

[Nutcracker]

This has led to questions about whether the size bias inherent to preservation in amber has limited inclusions to smaller individuals or species

I'd think that's inevitable - large species aren't going to get caught in resin / amber simply because you don't get quantities of resin large enough to trap them. A Tyrannosaur just isn't going to get stuck in 5 ml of resin 3