Ben Creisler
New papers about fossil birds:
Data for this study (lists of all nonâavian paravian specimens and all stemâbirds preserving ingested remains) are available in the Dryad Digital Repository:
https://doi.org/10.5061/dryad.7kj764d
The avian digestive system, like other aspects of avian biology, is highly modified relative to other reptiles. Together these modifications have imparted the great success of Neornithes, the most diverse clade of amniotes alive today. It is important to understand when and how aspects of the modern avian digestive system evolved among neornithine ancestors in order to elucidate the evolutionary success of this important clade and to understand the biology of stem birds and their closest dinosaurian relatives: Mesozoic Paraves. Although direct preservation of the soft tissue of the digestive system has not yet been reported, ingested remains and their anatomical location preserved in articulated fossils hint at the structure of the digestive system and its abilities. Almost all data concerning direct evidence of diet in Paraves comes from either the Upper Jurassic Yanliao Biota or the Lower Cretaceous Jehol Biota, both of which are known from deposits in northâeastern China. Here, the sum of the data gleaned from the thousands of exceptionally wellâpreserved fossils of paravians is interpreted with regards to the structure and evolution of the highly modified avian digestive system and feeding apparatus. This information suggests intrinsic differences between closely related stem lineages implying either strong homoplasy or that diet in each lineage of nonâornithuromorph birds was highly specialized. Regardless, modern digestive capabilities appear to be limited to the Ornithuromorpha, although the complete set of derived feeding related characters is restricted to the Neornithes.
====
GÃraldine Garcia, CÃcile Mourer-ChauvirÃ, Mohammed Adaci, Mustapha Bensalah, Fateh Mebrouk, Xavier Valentin, M'hammed Mahboubi & RodolpheTabuce (2019)
First discovery of avian egg and bone remains (Presbyornithidae) from the Gour Lazib (Eocene, Algeria).
Journal of African Earth Sciences (advance online publication)
doi:
https://doi.org/10.1016/j.jafrearsci.2019.103666 https://www.sciencedirect.com/science/article/pii/S1464343X19303218Highlights
Numerous avian eggshells and one well-preserved small ovoid-shaped egg (32âÃâ28âmm) were collected from three localities in the Gour Lazib area (HGL10, HGL51 and HGL62), western Algeria from the Glib Zegdou Formation dated from the late early or early middle Eocene.
This material was associated with a rich vertebrate fauna. The study of the eggshells using microscopies (PLM and SEM) led to attribute them to neognathous birds.
They are characterized by a thin shell (less than 0.5âmm thick) with a prismatic trilaminate microstructure.
The occurrence of an avian carpometacarpus belonging to the Presbyornithidae from HGL50, which is located one meter below the HGL 51 level, suggests that the egg remains may be referred to this bird family, which is so far unknown in the Palaeogene of the Afro-Arabian continent.
Abstract
Numerous avian eggshells and one well-preserved small ovoid-shaped egg (32âÃâ28âmm) were collected from three localities in the Gour Lazib area (HGL10, HGL51 and HGL62), western Algeria from the Glib Zegdou Formation dated from the late early or early middle Eocene. This material was associated with a rich vertebrate fauna. The study of the eggshells using microscopies (PLM and SEM) led to attribute them to neognathous birds. They are characterized by a thin shell (less than 0.5âmm thick) with a prismatic trilaminate microstructure. The occurrence of an avian carpometacarpus belonging to the Presbyornithidae from HGL50, which is located one meter below the HGL 51 level, suggests that the egg remains may be referred to this bird family, which is so far unknown in the Palaeogene of the Afro-Arabian continent.