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

The oldest dryolestid mammal from the Middle Jurassic of Siberia

<div><p>ABSTRACT—<i>Anthracolestes sergeii</i>, gen. et sp. nov., based on three isolated lower molars and several edentulous dentary fragments from the Middle Jurassic (Bathonian) Itat Formation at Berezovsk Quarry in Krasnoyarsk Territory, Russia, is the oldest and most basal representative of Dryolestidae. It shows four unambiguous synapomorphies of Dryolestidae: lower molars with unilaterally hypsodont crowns, unequal roots, and pronounced precingulid instead of cusp f, and dentary with unequal alveolar borders. The dental formula of the new taxon is i1–4, c (double-rooted), p1–4(?), and m1–4(?). <i>Anthracolestes sergeii</i>, gen. et sp. nov., is plesiomorphic relative to more derived and geologically younger dryolestids in having possibly fewer lower molars, less pronounced mesiodistal compression of lower molars, oblique protocristid, short mandibular symphysis, and shallow mandibular ramus of the dentary. Asia is most likely the place of origin for Dryolestidae, but this group is so far not known from that continent after the Middle Jurassic.</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></div

Basicranium of an elasmosaurid plesiosaur from the Campanian of European Russia

<p>Zverkov, N.G., Averianov, A.O. & Popov E.V., April 2017. Basicranium of an elasmosaurid plesiosaur from the Campanian of European Russia. Alcheringa 42, 528-542. ISSN 0311-5518</p> <p>The braincase of elasmosaurid plesiosaurs is poorly known. Here, we describe the exceptionally well-preserved elasmosaurid basicranium from the Rybushka Formation (lower Campanian) of Saratov Province, Russia. The material provides new anatomical information and peculiar features: single anterior foramen for the cerebral carotid arteries, anteroposteriorly elongated sella turcica and deep canal on the basioccipital process. This allow us to reconstruct a carotid circulation in plesiosaurs and propose new basicranial features (anteroposteriorly elongated sella turcica and single anterior foramen for the cerebral carotids), which could be potentially synapomorphic for a clade within the Elasmosauridae.</p> <p><i>Nikolay G. Zverkov* [</i>[email protected]<i>], Department of Palaeontology, Geological Faculty, Lomonosov Moscow State University, 1 Leninskie Gory, 119991 Moscow; Laboratory of Phanerozoic Stratigraphy, Department of Stratigraphy, Geological Institute of the Russian Academy of Sciences, Pyzhevsky lane 7, 119017 Moscow, Russia; Alexander O. Averianov [</i>[email protected]<i>], Zoological Institute of the Russian Academy of Sciences, Universitetskaya Emb. 1, Saint Petersburg 199034; Department of Sedimentary Geology, Geological Faculty, Saint Petersburg State University, 16 liniya VO 29, 199178 Saint Petersburg, Russia; Evgeny V. Popov [</i>[email protected]<i>], Department of Historical Geology and Paleontology, Geological Faculty, Saratov State University, 83 Astrakhanskaya Str., 410012 Saratov; Institute of Geology and Petroleum Technology, Kazan Federal University, Kremlevskaya Str. 4/5, 420008 Kazan, Russia.</i></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

The first dinosaur egg from the Lower Cretaceous of Western Siberia, Russia

<p>The Lower Cretaceous Ilek Formation in Western Siberia (Russia) has yielded various vertebrate fossils, including skeletal remains of dinosaurs. Here we report on a fragmentary theropod egg from the vertebrate locality Shestakovo 3 of the Ilek Formation in Kemerovo Province. We assign the specimen to the oogenus <i>Prismatoolithus</i> (oofamily Prismatoolithidae) as <i>Prismatoolithus ilekensis</i> oosp. nov., on the basis of the following unique combination of characters: ovoid-shaped egg; thin eggshell 300–330 μm thick; angustiprismatic morphotype; eggshell with three different layers; gradual transition between mammillary layer and prismatic layer; abrupt contact between prismatic layer and external layer; mammillary layer to prismatic layer to external layer thickness ratio is 1:3:0.6; prismatic layer with ill-defined squamatic texture; angusticanaliculate pore system; and smooth outer surface. Like other Early Creataceous <i>Prismatoolithus</i>, the egg of <i>Prismatoolithus ilekensis</i> oosp. nov. was laid by a small bodied theropod dinosaur (troodontid or primitive bird) and this taxonomic attribution is supported by results of our phylogenetic analysis. <i>Prismatoolithus ilekensis</i> oosp. nov. is the first Early Cretaceous ootaxon from Russia.</p> <p>urn:lsid:zoobank.org:act:734EAD40-86C3-488B-A61E-B5FF7378BC0E</p