A second nearly complete, articulated specimen of the basal troodontid (DNHM

A second nearly complete, articulated specimen of the basal troodontid (DNHM D2154) is reported from the Early Cretaceous (Hauterivian-Valanginian) lower Yixian Formation, Liaoning Province, China. attributes, full fusion of all neurocentral synostoses and the sacrum, and dense exteriors to cortical bone, suggest a small, mature individual. Microscopic 17-AAG examination of tibia and fibula histology confirms maturity and suggests an individual greater than two years aged with slowed growth. Despite being one of the smallest dinosaurs, exhibits multi-year growth and cortical bone consisting mainly of fibro-lamellar cells designated by lines of caught growth as with much larger and more basal theropods. This specimen lies in a similar but mirrored 17-AAG sleeping position to that of the holotype, conditioning the hypothesis that both specimens were preserved inside a stereotypical existence position. Like many Liaoning specimens, the new specimen also lacks considerable taphonomic and stratigraphic data, making further behavioral inference problematic. Intro The Jehol Group is composed of the stratigraphically conformable Yixian and Jiufotang Formations and is exposed in western portions of Liaoning Province, China. These formations are dominated by laminated and finely bedded siliciclastic sediments interspersed with extrusive basalts and tuffs [1]. They have produced a widely acclaimed fossilized fauna that includes a wide diversity of fish, invertebrates, vegetation [1], mammals [2], [3], diapsids [4], [5] including dinosaurs [6]C[8] with many specimens displaying outstanding soft-tissue and 17-AAG integument preservation [9]C[11]. These spectacular fossils are mainly strongly compressed [12] and come from the siliciclastic sediments thought to have been deposited by a series of inland, freshwater lacustrine environments [1]. In the lower Yixian Formation, a fossiliferous tuff coating, the Lujiatun mattresses, plants out near Beipiao City [1]. The Lujiatun mattresses lack obvious bed linens planes [1], and have been interpreted as volcaniclastic in source, probably representing volcanic mudflow events [13]. This results in beautiful three-dimensional preservation [13], [14]. However, observe Meng et al. [15] for alternate scenarios. Several specimens have emerged from the lower mattresses with three-dimensional preservation provides the chance for behavioral inferences [13], [15], [16]. One of these three-dimensionally maintained specimens is definitely a small troodontid, named by Xu and Norell [16]. It was maintained in a position that closely matched the stereotypical sleeping posture of modern parrots [16]. Here we statement on a second specimen of (DNHM D2514) in dorsal look at. Institutional Abbreviations DNHM, Dalian Natural History Museum, Dalian, China; IGM, Institute of Geology, Mongolia, Ulaan Battar; IVPP, Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, China; MOR, Museum of the Rockies, Bozeman, Montana, U.S.A. Materials and Methods Anatomical Terminology For anatomical placing, the terminology will follow the conventions of the Nomina Anatomica Avium [17] where feasible. In describing the orientation of the elements relative to each other as maintained, the terms front side and back or behind are used to define directions along an axis roughly parallel to the dorsal series of the vertebral column, where moving from your sacrum towards sharp curvature in the neck is definitely defined as ahead or the front. Consequently, moving from the throat towards sacrum in any collection roughly parallel to the dorsal vertebral column is definitely defined as the rear, with terms indicating that direction including rearward, back or behind. Histology To assess the ontogenetic age of DNHM D2154, we eliminated, molded and cast a section of the mid-diaphysis of the right tibia and fibula. A solid of the eliminated section was then put into the initial 17-AAG specimen to retain the overall morphology. RAC Cross-sections were prepared for each element using standard paleohistologic techniques [18]C[20], and examined with light microscopy. Descriptive terminology follows Francilion-Vieillot et al. [21], and 17-AAG age at death was assessed from annual lines of caught growth (LAGs) [22]. Phylogenetic Protocol Our analysis used the matrix from Xu et al. [23] with coding modifications to.

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