#iteravis

Many modern birds have large salt glands above their eyes to help them get rid of excess salt in their bodies. A new paper finds evidence of these salt glands in the 120-million-year-old bird Iteravis. This represents by far the oldest clear record of salt glands in any dinosaur, and I write more about it here.

By José Carlos Cortés on @quetzalcuetzpalin-art​

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Name: Iteravis huchzermeyri

Name Meaning: Journey Bird

FIrst Described: 2014

Described By: Zhou et al. 

Classification: Dinosauria, Theropoda, Neotheropoda, Averostra, Tetanurae, Orionides, Avetheropoda, Coelurosauria, Tyrannoraptora, Maniraptoriformes, Maniraptora, Pennaraptora, Paraves, Eumaniraptora, Averaptora, Avialae, Euavialae, Avebrevicauda, Pygostylia, Ornithothoraces, Euornithes, Ornithuromorpha 

Iteravis is our first in-order Euornithine, the line of dinosaurs that lead to modern birds! Euornithes articulated their wings the same way modern birds do, hence the naming convention - Opposite Birds versus True Birds. They also were very similar to modern birds in terms of plumage, including similar tail feathers. However, they weren’t quite modern birds yet - they still had teeth like other non-avian dinosaurs, amongst other things. Iteravis is a recently described Euornithine from the Yixian Formation of Liaoning, China, living approximately 128 million years ago, in the Aptian age of the Early Cretaceous. It was described based on a subadult skeleton preserved in a slab, with some feather impressions that are non-detailed. Many more skeletons of Iteravis have also been collected, representing many points in its growth sequence. By the time it reached subadult stage, it was mostly fully grown, reaching skeletal maturity within a year, like in modern birds, though it probably evolved independently in Iteravis and relatives. Of the skeletons of Iteravis, some were preserved with medullary bone - a type of tissue that is built up in female dinosaurs when they’re about to lay eggs - indicating that they may have been preserved in a nesting colony. However, not enough adults were sampled to confirm that hypothesis. Iteravis did not have teeth in the tip of its snout - a precursor to the toothlessness found in modern birds - but it did have teeth in the rest of its jaw. It was also preserved with gastroliths in its gizzard, but larger and fewer of them than other birds from its environment such as Jeholornis. It also has a fork-like tail feathers, though it’s possible that this is just a preservational thing and it had a fully fork tail like Schizooura or paired tail feathers like Confuciusornis. Its early position in the fossil record indicates that Eurornithes were more common than previously suspected; rather than the Enantiornithes being the dominant birds of the time. It was on the smaller size end for Euornithes in its environment, with a skull length at maximum of 45 millimeters, with other Euornithes in the area reaching as much as 70 millimeters in skull length. It may be synonymous with “Gansus” zheni, though this has not been tested in the literature yet. 

Sources: 

Zhou, S., J. K. O’Connor, M. Wang. 2014. A new species from an ornithuromorpha (Aves: Ornithothoraces) dominated locality of the Jehol Biota. Chinese Science Bulletin 59 (36): 5366 - 5378. 

O’Connor, J. K., M. Wang, S. Zhou, Z. Zhou. 2015. Osteohistology of the Lower Cretaceous Yixian Formation ornithuromorph (Aves) Iteravis huchzermeyeri. Palaeontologia Electronica 18.2.35A: 1 - 11. 

O’Connor, J. K., M. Wang, H. Hu. 2016. A new ornithuromorph (Aves) with an elongate rostrum from the Jehol Biota, and the early evolution of rostralization in birds. Journal of Systematic Palaeontology DOI: 10.1080/14772019.2015.1129518. 

https://theropoddatabase.blogspot.com/2014/12/gansus-zheni-is-iteravis.html