François Escuillié

A Jurassic avialan dinosaur from China resolves the early phylogenetic history of birds.

The recent discovery of small paravian theropod dinosaurs with well-preserved feathers in the Middle–Late Jurassic Tiaojishan Formation of Liaoning Province (northeastern China) has challenged the pivotal position of Archaeopteryx, regarded from its discovery to be the most basal bird. Removing Archaeopteryx from the base of Avialae to nest within Deinonychosauria implies that typical bird flight, powered by the forelimbs only, either evolved at least twice, or was subsequently lost or modified in some deinonychosaurians. Here we describe the complete skeleton of a new paravian from the Tiaojishan Formation of Liaoning Province, China. Including this new taxon in a comprehensive phylogenetic analysis for basal Paraves does the following: (1) it recovers it as the basal-most avialan; (2) it confirms the avialan status of Archaeopteryx; (3) it places Troodontidae as the sister-group to Avialae; (4) it supports a single origin of powered flight within Paraves; and (5) it implies that the early diversification of Paraves and Avialae took place in the Middle–Late Jurassic period.

A gigantic bird from the Upper Cretaceous of Central Asia.

We describe an enormous Late Cretaceous fossil bird from Kazakhstan, known from a pair of edentulous mandibular rami (greater than 275 mm long), which adds significantly to our knowledge of Mesozoic avian morphological and ecological diversity. A suite of autapomorphies lead us to recognize the specimen as a new taxon. Phylogenetic analysis resolves this giant bird deep within Aves as a basal member of Ornithuromorpha. This Kazakh fossil demonstrates that large body size evolved at least once outside modern birds (Neornithes) and reveals hitherto unexpected trophic diversity within Cretaceous Aves.

Molecular composition and ultrastructure of Jurassic paravian feathers

Feathers are amongst the most complex epidermal structures known, and they have a well-documented evolutionary trajectory across non-avian dinosaurs and basal birds. Moreover, melanosome-like microbodies preserved in association with fossil plumage have been used to reconstruct original colour, behaviour and physiology. However, these putative ancient melanosomes might alternatively represent microorganismal residues, a conflicting interpretation compounded by a lack of unambiguous chemical data. We therefore used sensitive molecular imaging, supported by multiple independent analytical tests, to demonstrate that the filamentous epidermal appendages in a new specimen of the Jurassic paravian Anchiornis comprise remnant eumelanosomes and fibril-like microstructures, preserved as endogenous eumelanin and authigenic calcium phosphate. These results provide novel insights into the early evolution of feathers at the sub-cellular level, and unequivocally determine that melanosomes can be preserved in fossil feathers.

Perinatal Specimens of Saurolophus angustirostris (Dinosauria: Hadrosauridae), from the Upper Cretaceous of Mongolia

Background The Late Cretaceous Nemegt Formation, Gobi Desert, Mongolia has already yielded abundant and complete skeletons of the hadrosaur Saurolophus angustirostris, from half-grown to adult individuals. Methodology/Principal Findings Herein we describe perinatal specimens of Saurolophus angustirostris, associated with fragmentary eggshell fragments. The skull length of these babies is around 5% that of the largest known S. angustirostris specimens, so these specimens document the earliest development stages of this giant hadrosaur and bridge a large hiatus in our knowledge of the ontogeny of S. angustirostris. Conclusions/Significance The studied specimens are likely part of a nest originally located on a riverbank point bar. The perinatal specimens were buried by sediment carried by the river current presumably during the wet summer season. Perinatal bones already displayed diagnostic characters for Saurolophus angustirostris, including premaxillae with a strongly reflected oral margin and upturned premaxillary body in lateral aspect. The absence of a supracranial crest and unfused halves of the cervical neural arches characterize the earliest stages in the ontogeny of S. angustirostris. The eggshell fragments associated with the perinatal individuals can be referred to the Spheroolithus oogenus and closely resemble those found in older formations (e.g. Barun Goyot Fm in Mongolia) or associated with more basal hadrosauroids (Bactrosaurus-Gilmoreosaurus in the Iren Dabasu Fm, Inner Mongolia, China). This observation suggests that the egg microstructure was similar in basal hadrosauroids and more advanced saurolophines. Competing Interests One of the authors (FE) is employed by the commercial organization Eldonia. Eldonia provided support in the form of a salary for FE, but did not have any additional role or influence in the study design, data collection and analysis, decision to publish, or preparation of the manuscript and it does not alter the authors’ adherence to all the PLoS ONE policies on sharing data and materials.

New material of the choristodere Lazarussuchus (Diapsida, Choristodera) from the Paleocene of France

ABSTRACT Choristodera is a clade of freshwater aquatic reptiles with a strictly Laurasian distribution and a temporal record extending from at least Middle Jurassic to Miocene. The large Cretaceous-Eocene neochoristoderes Champsosaurus and Simoedosaurus are the most familiar taxa, but many smaller representatives have since been recognized. Neochoristoderes disappeared from the fossil record in the Eocene, but choristoderes survived into the European Neogene in the form of the small, superficially lizard-like Lazarussuchus. This taxon was originally described from the late Oligocene of France but has subsequently been recorded from the early Miocene of the Czech Republic and the late Oligocene of Germany. Despite its age, most phylogenetic analyses place Lazarussuchus at or close to the base of the choristoderan tree, implying a very long unrecorded history. A new specimen of Lazarussuchus from the late Paleocene locality of Menat, France, partly fills that hiatus. The genus was thus present in the waterways of western Europe for at least 30 Ma, and was probably considerably more widespread than current records suggest. A new phylogenetic analysis confirms its placement outside Neochoristodera, but the relationships of non-neochoristoderan taxa remain incompletely resolved.

A new Jurassic theropod from China documents a transitional step in the macrostructure of feathers

Genuine fossils with exquisitely preserved plumage from the Late Jurassic and Early Cretaceous of northeastern China have recently revealed that bird-like theropod dinosaurs had long pennaceous feathers along their hindlimbs and may have used their four wings to glide or fly. Thus, it has been postulated that early bird flight might initially have involved four wings (Xu et al. Nature 421:335–340, 2003; Hu et al. Nature 461:640–643, 2009; Han et al. Nat Commun 5:4382, 2014). Here, we describe Serikornis sungei gen. et sp. nov., a new feathered theropod from the Tiaojishan Fm (Late Jurassic) of Liaoning Province, China. Its skeletal morphology suggests a ground-dwelling ecology with no flying adaptations. Our phylogenetic analysis places Serikornis, together with other Late Jurassic paravians from China, as a basal paravians, outside the Eumaniraptora clade. The tail of Serikornis is covered proximally by filaments and distally by slender rectrices. Thin symmetrical remiges lacking barbules are attached along its forelimbs and elongate hindlimb feathers extend up to its toes, suggesting that hindlimb remiges evolved in ground-dwelling maniraptorans before being co-opted to an arboreal lifestyle or flight.