A historical specimen of enantiornithine bird from the Early Cretaceous of Mongolia representing a new taxon with a specialized neck morphology

We describe Holbotia ponomarenkoi gen. et sp. nov., the first articulated specimen of an enantiornithine bird from Mongolia, unearthed in 1977 from Early Cretaceous deposits and formerly thought to be a pterosaur. The specimen shows a series of morphological details that are either unique to the new taxon or very poorly known for Enantiornithes. A previously unobserved specialized cervical morphology, the development of a crest on the caudal surface of the distal tibia, and the presence of unusually widely spaced small teeth in the lower jaw are unique features of Holbotia. The results of a phylogenetic analysis indicate that Holbotia is more closely related to the Late Cretaceous edentulous Gobipteryx than to the Early Cretaceous enantiornithines with reduced dentition (Longipterygidae), which implies a different evolutionary pathway for the loss of teeth in Enantiornithes, as compared with Ornithuromorpha. The only preserved cervical vertebra of Holbotia ponomarenkoi displays partly ventrally facing prezygapophyseal articular surfaces, otherwise found only in the darters (Anhingidae), which implies an unusually increased degree of neck mobility. Morphology of the palate, described in detail for an Early Cretaceous enantiornithine bird for the first time, is roughly similar to that of Archaeopteryx and non-avian paravians. It shows that the evolution of specialized rostral morphology in Early Cretaceous enantiornithines was possible with retention of the primitive palatal structure, in contrast to modern birds (Neornithes), where the diversification of skull types was coupled with the evolution of several types of palate

A historical specimen of enantiornithine bird from the Early Cretaceous of Mongolia representing a new taxon with a specialized neck morphology

<p>We describe <i>Holbotia ponomarenkoi</i> gen. et sp. nov., the first articulated specimen of an enantiornithine bird from Mongolia, unearthed in 1977 from Early Cretaceous deposits and formerly thought to be a pterosaur. The specimen shows a series of morphological details that are either unique to the new taxon or very poorly known for Enantiornithes. A previously unobserved specialized cervical morphology, the development of a crest on the caudal surface of the distal tibia, and the presence of unusually widely spaced small teeth in the lower jaw are unique features of <i>Holbotia</i>. The results of a phylogenetic analysis indicate that <i>Holbotia</i> is more closely related to the Late Cretaceous edentulous <i>Gobipteryx</i> than to the Early Cretaceous enantiornithines with reduced dentition (Longipterygidae), which implies a different evolutionary pathway for the loss of teeth in Enantiornithes, as compared with Ornithuromorpha. The only preserved cervical vertebra of <i>Holbotia ponomarenkoi</i> displays partly ventrally facing prezygapophyseal articular surfaces, otherwise found only in the darters (Anhingidae), which implies an unusually increased degree of neck mobility. Morphology of the palate, described in detail for an Early Cretaceous enantiornithine bird for the first time, is roughly similar to that of <i>Archaeopteryx</i> and non-avian paravians. It shows that the evolution of specialized rostral morphology in Early Cretaceous enantiornithines was possible with retention of the primitive palatal structure, in contrast to modern birds (Neornithes), where the diversification of skull types was coupled with the evolution of several types of palate.</p> <p><a href="http://zoobank.org/urn:lsid:zoobank.org:pub:42845FFC-4E4B-4FEE-9D76-0B5A7D9E127B" target="_blank">http://zoobank.org/urn:lsid:zoobank.org:pub:42845FFC-4E4B-4FEE-9D76-0B5A7D9E127B</a></p

A confuciusornithiform (Aves, Pygostylia)-like tarsometatarsus from the Early Cretaceous of Siberia and a discussion of the evolution of avian hind limb musculature

<div><p>ABSTRACT</p><p>We describe a new isolated tarsometatarsus from the Early Cretaceous (Barremian-Aptian) Ilek Formation Shestakovo-3 locality in western Siberia. The new specimen represents a new taxon, <i>Evgenavis nobilis</i>, gen. et sp. nov., significantly increasing the Mesozoic avifauna from Russia. The specimen shares morphologies with a number of basal ornithothoracine taxa, but shows most similarity to the basal pygostylian <i>Confuciusornis sanctus</i>, the oldest known beaked bird and most common taxon from the Yixian Formation. <i>Evgenavis</i> may represent the first record of Confuciusornithiformes outside of the Jehol Group and its equivalent deposits. However, this is not supported by cladistic analysis, which weakly resolves the new species and <i>Mystiornis</i> both within the diverse Enantiornithes, indicating that additional material is required to assess the systematic position of <i>Evgenavis nobilis</i> (Aves incertae sedis). The three-dimensional preservation of the specimen allows for a partial reconstruction of the pedal musculature, revealing a primitive stage in the evolution of the neornithine condition.</p><p>SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at <a href="http://www.tandfonline.com/UJVP" target="_blank">http://www.tandfonline.com/UJVP</a>.</p></div

A new unusual waterbird (Aves, ?Suliformes) from the Eocene of Kazakhstan

<p><a href="http://zoobank.org/urn:lsid:zoobank.org:pub:55265D97-F2EF-459D-9728-E4C433DB22F9" target="_blank">http://zoobank.org/urn:lsid:zoobank.org:pub:55265D97-F2EF-459D-9728-E4C433DB22F9</a></p> <p>SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at <a href="http://www.tandfonline.com/UJVP" target="_blank">www.tandfonline.com/UJVP</a></p> <p>Citation for this article: Zvonok, E. A., N. V. Zelenkov, and I. G. Danilov. 2015. A new unusual waterbird (Aves, ?Suliformes) from the Eocene of Kazakhstan. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2015.1035783.</p