#Yangavis confucii

[metodogolo]

Paleontólogos hallan el fósil de un ave con pico de 119 millones de años de antigüedad

A partir de un esqueleto casi completo hallado en el noreste de China se ha identificado una nueva especie de ave confuciusornítida a la que se ha dado el nombre de Confuciusornis shifan.

Confuciusornis shifan vivió en lo que hoy es China durante el Cretácico Temprano, hace unos 119 millones de años.

La nueva especie pertenecía a Confuciusornis, un género extinto de aves con pico del tamaño de un cuervo de la familia Confuciusornithidae.

Confuciusornis shifan pesaba menos de 200 gramos y era más pequeño que la mayoría de las demás especies de confuciusornítidos.

"Confuciusornithidae es un clado de aves pigostíleas del Cretácico Temprano conocidas en la biota Jehol de Asia Oriental, y representa a las primeras aves sin dientes y con pico conocidas", explican los paleontólogos de la Universidad Normal de Shenyang Dongyu Hu y Xing Xu y sus colegas de China y Canadá.

"Se han descrito y asignado a esta familia cinco géneros y once especies, recuperados de las formaciones Dabeigou, Yixian y Jiufotang, aunque la validez de algunas especies es cuestionable".

"Están representados por miles de especímenes excepcionalmente conservados que proporcionan colectivamente una rica información sobre la morfología, taxonomía, capacidad de vuelo, crecimiento, dieta y ecología de los confuciusornítidos."

El esqueleto casi completo y articulado, conservado en una única losa, de Confuciusornis shifan fue recuperado de la Formación Jiufotang, cerca de la aldea de Xiaotaizi, en la provincia china de Liaoning.

"En comparación con otros confuciusornítidos, esta nueva especie y la recientemente descrita Yangavis confucii muestran evidencias de una mayor capacidad de vuelo, aunque las alas de las dos especies difieren entre sí en muchos aspectos", afirman los investigadores.

"Nuestros análisis aerodinámicos en el marco de la filogenia indican que diversos modos de adaptación al vuelo surgieron a través de la diversidad de confuciusornítidos, y en menor grado en el curso de su ontogenia, y sugieren específicamente que tanto una tendencia hacia la mejora de la capacidad de vuelo como un cambio en la estrategia de vuelo se produjeron en la evolución de los confuciusornítidos."

"Confuciusornis shifan difiere de manera más destacada de otras aves mesozoicas por tener un hueso extra en forma de almohadilla en el primer dígito del ala, una característica muy inusual que puede haber ayudado a satisfacer las demandas funcionales del vuelo en una etapa en la que el crecimiento del esqueleto era aún incompleto", concluyeron.

"El nuevo hallazgo ejemplifica de forma sorprendente la diversidad morfológica, de desarrollo y funcional de las primeras aves con pico".

Referencia:

Wang, R., Hu, D., Zhang, M. et al. A new confuciusornithid bird with a secondary epiphyseal ossification reveals phylogenetic changes in confuciusornithid flight mode. Commun Biol 5, 1398 (2022). https://doi.org/10.1038/s42003-022-04316-6

[a-dinosaur-a-day]

Yangavis confucii

By Ripley Cook

Etymology: Zhongjian Yang’s Bird

First Described By: Wang & Zhou, 2019

Classification: Dinosauromorpha, Dinosauriformes, Dracohors, Dinosauria, Saurischia, Eusaurischia, Theropoda, Neotheropoda, Averostra, Tetanurae, Orionides, Avetheropoda, Coelurosauria, Tyrannoraptora, Maniraptoromorpha, Maniraptoriformes, Maniraptora, Pennaraptora, Paraves, Eumaniraptora, Averaptora, Avialae, Euavialae, Avebrevicauda, Pygostylia, Confuciusornithiformes, Confuciusornithidae

Status: Extinct

Time and Place: About 128 million years ago, in the Barremian age of the Early Cretaceous 

Yangavis is known from the Sihedang bed just above the Basalt Base of the Yixian Formation in Liaoning, China 

Physical Description: Yangavis was a Confuciusornithid, a kind of proto-bird that convergently evolved a lot of birdie characteristics independent of the direct ancestors of modern birds. These were small-bodied dinosaurs, with the pygostyle that characterizes living birds - the shortened, fused tail that acts as a ball-and-socket joint to give the tail maximum flexibility and movement. Yangavis was about the same size as other Confuciusornithids - the size of a modern day robin or starling - except that it had huge, half-a-meter-long wings, much bigger than other members of the group. Yangavis had a small head and a toothless beak, and that beak is the main trait that Confuciusornithids evolved, much like modern birds, but independently.

Yangavis was a bit weird compared to other members of its group in other ways as well. It had a more rectangular jaw, and had ridges running on the outside of its beak. It had very long claws on its fingers, unlike those of other Confuciusornithids; it also had longer toes and a larger claw on its first toe than its relatives. This shows that reduction of these features was also unique for more derived Confuciusornithids, rather than inherited from the general group of proto-birds.

Diet: The diet of Yangavis is a bit of a question, as is the diet of all Confuciusornithids, due to the fact that they are toothless. However, the current dominating hypothesis is that these animals were piscivores, due to their association with lakes, and the remains of fish being found in the stomach of at least one Confuciusornis. 

By José Carlos Cortés 

Behavior: Yangavis was a small birdie dinosaur, and as such it would have been very skittish, probably in danger from larger dinosaur predators in its environment. As a Confuciusornithid, it did have rudimentary flight ability, but it was not the strongest of flappers. Instead, it might have used its longer wings in order to soar more over the lake system, only flapping when absolutely necessary. Though Yangavis hasn’t been found in large groups like its relatives, it probably would have been fairly social, all flying together to look for food. This flight would have been very odd due to the inability to raise their arms high; perhaps they utilized a flight ability not seen in modern birds. Yangavis would then dip down to the water, grabbing food from under the surface of the lake.

Though the original fossil of Yangavis was not found with extensive feather impressions, its relatives show possible sexual dimorphism in terms of feather shape on the tail. Presumed mails had long, ribbon-like feathers coming off of the tail, which could be raised and lowered by the flexible tailbone to display to females. It’s entirely possible that Yangavis also showcased similar behavior to one another, in order to attract mates and threaten rivals.

Ecosystem: Yangavis is from the Yixian Formation, one of the extremely diverse northern Chinese ecosystems from the Early Cretaceous that showcases the evolution of so many modern groups, especially birds, mammals, and flowers. This was a temperate forest environment, near an extensive system of volcanoes, surrounding complicated lake systems. However, Yangavis is from one of the earliest beds of that formation, a time when very few other animals are known. It lived alongside other birds - namely, the enantiornithine Monoenantiornis and the euornithine Iteravis, as well as a turtle, Jeholochelys, and two pterosaurs, Ikrandraco and Guidraco. Other creatures were probably present, of course, but they have yet to be found.

Other: Yangavis indicates that Confuciusornithids - this group of very basal proto-birds - was more morphologically diverse than previously thought.

~ By Meig Dickson

Sources under the Cut 

Dalsätt, J., Z. Zhhou, F. Zhang, P. G. P. Ericson. 2006. Food remains in Confuciusornis sanctus suggest a fish diet. Naturwissenschaften 93 (9): 444- 446.

Hu, H., J. K. O'Connor. 2017. First species of Enantiornithes from Sihedang elucidates skeletal development in Early Cretaceous enantiornithines. Journal of Systematic Palaeontology 15(11):909-926

Li, Q., J. A. Clarke, K.-Q. Gao, C.-F. Zhou, Q. Meng, D. Li, L. D'Alba and M. D. Shawkey. 2014. Melanosome evolution indicates a key physiological shift within feathered dinosaurs. Nature 507:350-353

Shao, S., L. Li, Y. Yang and C.-F. Zhou. 2018. Hyperphalangy in a new sinemydid turtle from the Early Cretaceous Jehol Biota. PeerJ 6:e5371:1-21

Wang, M., Z. Zhou. 2019. A new confuciusornithid (Aves: Pygostylia) from the Early Cretaceous increases the morphological disparity of the Confuciusornithidae. Zoological Journal of the Linnean Society 185: 417 - 430.

Wang, X., R. L. Nudds, G. J. Dyke. 2011. The primary feather lengths of early birds with respect to avian wing shape evolution. Journal of Evolutionary Biology 24 (6): 286 - 289.

Wang, X., A. W. A. Kellner, S. Jiang and X. Cheng. 2012. New toothed reptile from Asia: close similarities between early Cretaceous pterosaur faunas from China and Brazil. Naturwissenschaften 99:249-257

Wang, X., T. Rodrigues, S. Jiang, X. Cheng, and A. W. A. Kellner. 2014. An Early Cretaceous pterosaur with an unusual mandibular crest from China and a potential novel feeding strategy. Scientific Reports 4(6329)

Zhou, S., J. K. O'Connor, and M. Wang. 2014. A new species from an ornithuromorph (Aves: Ornithothoraces) dominated locality of the Jehol Biota. Chinese Science Bulletin

Zinoviev, A. V. 2009. An attempt to reconstruct the lifestyle of confuciusornithids (Aves, Confuciusornithiformes). Paleontological Journal 43 (4): 444 - 452.