Fossil From 100 Million Years Ago Tells Us Extinct Baby Bird Could Hunt When It Hatched
Jurassic Park, here we come! A fossil of a baby bird that lived alongside the dinosaurs was recently discovered embedded inside a three-inch-long piece of 100-million-year-old Burmese amber
by GrrlScientist for Forbes | @GrrlScientist
(Credit: Lida Xing et al. (2017), doi: 10.1016/j.gr.2017.06.001)
Some very exciting news just popped up on the Twitter science scene: a spectacular new bird fossil has been discovered in a chunk of Burmese amber.
So life-like is this fossil that it is possible to infer what the bird was doing in the last moments of its life. According to a co-author of the manuscript, Kuowei Tseng, an associate professor at the University of Taipei, the hatchling appeared to have been hunting at the time of death.
“There were no obvious signs of struggle,” Professor Tseng told XinhuaNet, a Chinese newspaper that also publishes in English. “The overall posture of the bird resembled hunting, with its lifted body, open claws and beak and spread wings. It was possibly engulfed by falling resin at the exact moment it was hunting.”
This amber specimen was dated to be around 100 million years old; from the Cretaceous Period (79 million years to 145 million years ago). The amber-embedded fossil includes nearly half of the right side of a hatchling bird and is the most complete specimen discovered so far. It includes bones and soft tissues from the skull, neck, feet, and one wing. These features are so detailed and complete that they enable easy identification of this bird as a member of the extinct avian lineage, enantiornithes (“opposite birds”). This clade was named for the distinctive way that their shoulder bones articulate, or fit together, which is the reverse to what we see in all modern birds (neornithes).
The enantiornithes were an ancient group of pre-modern toothed avialans that lived alongside the ancestors of modern birds. The enantiornithes were quite a successful group; they were more diverse than the neornithines. But unlike modern birds, the enantiornithes were unlucky: they died out during the Cretaceous–Tertiary (K-T) mass extinction event that killed non-avian dinosaurs roughly 66 million years ago.
The quality of this particular fossil raises the question: what can this superb fossil tell us about this bird’s ecology and behavior?
This is the most complete and detailed bird fossil unearthed to date
According to National Geographic, which helped fund this study, the specimen was purchased in Myanmar in 2014. The purchaser, Guang Chen, curator of Hupoge Amber Museum in the city of Tengchong in western Yunnan, first learned of this amber specimen because it was reported to contain a peculiar “lizard claw” inclusion.
“Many people thought it was a lizard,” Mr. Chen told XinhuaNet.
“But the scales, thread-like feathers and sharp claws on the feet were so noticeable that I thought they must belong to a bird,” a sharp-eyed Mr. Chen said.
Mr. Chen later showed the specimen to Lida Xing, an associate professor at the China University of Geosciences. Professor Xing confirmed Mr. Chen’s initial identification: the claw belonged to a bird.
Professor Xing then assembled and led an international team of scientists who conducted further studies using Micro x-ray Computed Tomography (micro-CT).
Due to the size of the amber (originally, it measured roughly 3.4 inches [86 mm] long and weighed approximately 2.8 ounces [78.16 g] before it was cut in half), multiple scans were required of different parts of the bird before the complete three dimensional reconstruction of the specimen could be created.
The micro-CT reconstruction of this specimen is so detailed that it looks like something out of the popular film, Jurassic Park. However, unlike the film’s implausible premise, this bird has completely transformed into stone, so it does not contain any surviving DNA or proteins that might tempt ambitious scientists to clone a living representative.
The specimen reveals a surprising mix of primitive and modern feather types
The fossilized specimen’s soft tissues are so detailed that they enable exhaustive studies of the structure of the external opening of the ear, the eyelid, the skin and the fine details of the scales (skutes) on the bird’s feet. This elegant specimen even shows the cracking in the skutes that occurred during the process of fossilization.
But perhaps most surprising were the feathers: the scans revealed the fine details of feather arrangements and how they are implanted into the skin; the feather microstructure; and even the plumage pigmentation patterns.
The scans reveal an unexpected diversity of primitive and derived (modern) feathers were present in the plumage of enantiornithines, the researchers noted in their manuscript. The plumage includes filamentous body feathers that resemble ancient precursors to modern feathers, mature flight feathers, and newly growing ornamental flight feathers.
The micro-CT scans indicate that this hapless hatchling was engulfed by tree resin within a few days after hatching, when it was in the earliest stages of feather growth. The researchers also noted that the hatchling bird’s sparse body plumes were soft and fluffy — similar to theropod dinosaur feathers, which were fluffy because they lacked a central shaft, or rachis.
Despite being a hatchling, the fossil bird already possessed a full set of flight feathers on its wings, indicating that it could probably fly from the moment it hatched. Since it could fly from birth, the young precocial bird also could take care of itself and thus, likely did not require parental care — a stark contrast to modern birds, with the exception of the mound-building megapodes.
This specimen is so exquisite that the bird’s plumage coloring and color patterns made it possible for an artist to recreate a precise impression of what the bird looked like in life. Its plumage coloring was rather ordinary; ranging from white and brown to dark grey. One researcher even described this fossil bird as a “little brown job” — a term that is commonly (and sometimes dismissively) used by bird watchers.
(Credit: Cheung Chung Tat)
Nevertheless, the bird’s plumage coloring did inspire this specimen’s nickname, according to National Geographic: the researchers nicknamed it, ‘Belone’, after a Burmese name for the plainly colored amber-hued Oriental skylark, Alauda gulgula.
What can we infer about enantiornithine bird behavior and ecology from just one fossil?
“Overall, the new specimen brings a new level of detail to our understanding of the anatomy of the juvenile stages of the most species-rich clade of pre-modern birds and contributes to mounting data that enantiornithine development drastically differed from that of [modern birds],” the study’s authors write in their manuscript (ref). They also note that the unusual structures of the fossil feathers may provide a clearer understanding of feather evolution as well as interesting glimpses into the developmental and behavioral ecology of enantiornithines.
The plumage preserved in this specimen adds to mounting evidence that enantiornithine hatchlings could fly upon hatching and were highly precocial, requiring little or no parental care. This contrasts dramatically with most modern birds, whose hatchlings remain in the nest and depend upon their parents for some period of time before developing the ability to fly. Further, the scarcity of body feathers represents a distinct departure from living precocial birds.
It is interesting to note that enantiornithines were unique because their chicks were both highly independent and arboreal. In contrast, modern arboreal birds have altricial chicks that hatch in an undeveloped state and require care and feeding by the parents, whereas the super-precocial megapodes are primarily terrestrial and are poor fliers.
The researchers point out that enantiornithine hatchlings experienced slow growth, so they had to survive a prolonged period of vulnerability: this is reflected by the large number of juvenile enantiornithines found in the fossil record. In contrast, the young of other Cretaceous bird lineages are unknown.
It’s also likely that enantiornithines’ developmental limitations prevented them from exploiting some of the environments where modern birds live. For example, enantiornithines probably were unable to survive in extreme environments, nor were they aquatic.
Overall, this one small fossil of one very unlucky baby bird is a huge, and exciting, discovery. It reveals that enantiornithines were birds in a general sense, but they differed dramatically from modern birds in just about every possible facet of their developmental and behavioral ecology.
Source:
Lida Xing, Jingmai K. O’Connor, Ryan C. McKellar, Luis M. Chiappe, Kuowei Tseng, Gang Li, Ming Bai (2017). A mid-Cretaceous enantiornithine (Aves) hatchling preserved in Burmese amber with unusual plumage, Gondwana Research, published online on 6 June 2017 as a manuscript before print | doi:10.1016/j.gr.2017.06.001
Enjoy my writing? Please give me a few handclaps to recommend this piece. Follow me on Medium for more like this.
.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..
GrrlScientist is very active on twitter @GrrlScientist and you can follow all her writing by subscribing to her TinyLetter
Originally published at Forbes on 10 June 2017.
