Lujiatun Psittacosaurids: Understanding Individual and Taphonomic Variation Using 3D Geometric Morphometrics

Psittacosaurus is one of the most abundant and speciose genera in the Dinosauria, with fifteen named species. The genus is geographically and temporally widespread with large sample sizes of several of the nominal species allowing detailed analysis of intra- and interspecific variation. We present a reanalysis of three separate, coeval species within the Psittacosauridae; P. lujiatunensis, P. major, and Hongshanosaurus houi from the Lujiatun beds of the Yixian Formation, northeastern China, using three-dimensional geometric morphometrics on a sample set of thirty skulls in combination with a reevaluation of the proposed character states for each species. Using these complementary methods, we show that individual and taphonomic variation are the joint causes of a large range of variation among the skulls when they are plotted in a morphospace. Our results demonstrate that there is only one species of Psittacosaurus within the Lujiatun beds and that the three nominal species represent different taphomorphotypes of P. lujiatunensis. The wide range of geometric morphometric variation in a single species of Psittacosaurus implies that the range of variation found in other dinosaurian groups may also be related to taphonomic distortion rather than interspecific variation. As the morphospace is driven primarily by variation resulting from taphonomic distortion, this study demonstrates that the geometric morphometric approach can only be used with great caution to delineate interspecific variation in Psittacosaurus and likely other dinosaur groups without a complementary evaluation of character states. This study presents the first application of 3D geometric morphometrics to the dinosaurian morphospace and the first attempt to quantify taphonomic variation in dinosaur skulls

Cranial ontogenetic variation in early saurischians and the role of heterochrony in the diversification of predatory dinosaurs

Non-avian saurischian skulls underwent at least 165 million years of evolution and shapes varied from elongated skulls, such as in the theropod Coelophysis, to short and box-shaped skulls, such as in the sauropod Camarasaurus. A number of factors have long been considered to drive skull shape, including phylogeny, dietary preferences and functional constraints. However, heterochrony is increasingly being recognized as an important factor in dinosaur evolution. In order to quantitatively analyse the impact of heterochrony on saurischian skull shape, we analysed five ontogenetic trajectories using two-dimensional geometric morphometrics in a phylogenetic framework. This allowed for the comparative investigation of main ontogenetic shape changes and the evaluation of how heterochrony affected skull shape through both ontogenetic and phylogenetic trajectories. Using principal component analyses and multivariate regressions, it was possible to quantify different ontogenetic trajectories and evaluate them for evidence of heterochronic events allowing testing of previous hypotheses on cranial heterochrony in saurischians. We found that the skull shape of the hypothetical ancestor of Saurischia likely led to basal Sauropodomorpha through paedomorphosis, and to basal Theropoda mainly through peramorphosis. Paedomorphosis then led from Orionides to Avetheropoda, indicating that the paedomorphic trend found by previous authors in advanced coelurosaurs may extend back into the early evolution of Avetheropoda. Not only are changes in saurischian skull shape complex due to the large number of factors that affected it, but heterochrony itself is complex, with a number of possible reversals throughout non-avian saurischian evolution. In general, the sampling of complete ontogenetic trajectories including early juveniles is considerably lower than the sampling of single adult or subadult individuals, which is a major impediment to the study of heterochrony on non-avian dinosaurs. Thus, the current work represents an exploratory analysis. To better understand the cranial ontogeny and the impact of heterochrony on skull evolution in saurischians, the data set that we present here must be expanded and complemented with further sampling from future fossil discoveries, especially of juvenile individuals

Projected northward shifts in eastern red-backed salamanders due to changing climate

This work was supported by a research grant to BPH from the Research Enhancement Program at Louisiana State University. AE was funded by Organismo Autónomo Parques Nacionales of Spain through project 2745/2021.Many species' distributions are being impacted by the acceleration of climate change. Amphibians in particular serve numerous ecosystem functions and are useful indicators of environmental change. Understanding how their distributions have been impacted by climate change and will continue to be impacted is thus important to overall ecosystem health. Plethodon cinereus (Eastern Red-Backed Salamander) is a widespread species of lungless salamander (Plethodontidae) that ranges across northeastern North America. To better understand future potential lungless salamander range shifts, we quantify environmental favorability, the likelihood of membership in a set of sites where environmental conditions are favorable for a species, for P. cinereus in multiple time periods, and examine shifts in the species' distribution. First, utilizing a large data set of georeferenced records, we assessed which bioclimatic variables were associated with environmental favorability in P. cinereus. We then used species distribution modeling for two time periods (1961-1980 and 2001-2020) to determine whether there was a regional shift in environmental favorability in the past 60 years. Models were then used to project future distributions under eight climate change scenarios to quantify potential range shifts. Shifts were assessed using fuzzy logic, avoiding thresholds that oversimplify model predictions into artificial binary outputs. We found that P. cinereus presence is strongly associated with environmental stability. There has been a substantial northward shift in environmental favorability for P. cinereus between 1961-1980 and 2001-2020. This shift is predicted to continue by 2070, with larger shifts under higher greenhouse gas emission scenarios. As climate change accelerates, it is differentially impacting species but has especially strong impacts on dispersal-limited species. Our results show substantial northward shifts in climatic favorability in the last 60 years for P. cinereus, which are likely to be exacerbated by ongoing climate change. Since P. cinereus is dispersal-limited, these models may imply local extirpations along the southern modern range with limited northward dispersal. Continued monitoring of amphibians in the field will reveal microclimatic effects associated with climate change and the accuracy of the model predictions presented here.Publisher PDFPeer reviewe

The Slothful Claw: Osteology and Taphonomy of \u3cem\u3eNothronychus mckinleyi\u3c/em\u3e and \u3cem\u3eN. graffami\u3c/em\u3e (Dinosauria: Theropoda) and Anatomical Considerations for Derived Therizinosaurids

Nothronychus was the first definitive therizinosaurian discovered in North America and currently represents the most specialized North American therizinosaurian genus. It is known from two species, No. mckinleyi from the Moreno Hill Formation (middle Turonian) in west-central New Mexico, and No. graffami from the Tropic Shale (early Turonian) in south-central Utah. Both species are represented by partial to nearly complete skeletons that have helped elucidate evolutionary trends in Therizinosauria. In spite of the biogeographical and evolutionary importance of these two taxa, neither has received a detailed description. Here, we present comprehensive descriptions of No. mckinleyi and No. graffami, the latter of which represents the most complete therizinosaurid skeleton known to date. We amend previous preliminary descriptions of No. mckinleyi and No. graffami based on these new data and modify previous character states based on an in-depth morphological analysis. Additionally, we review the depositional history of both specimens of Nothronychus and compare their taphonomic modes. We demonstrate that the species were not only separated geographically, but also temporally. Based on ammonoid biozones, the species appear to have been separated by at least 1.5 million years and up to 3 million years. We then discuss the impacts of diagenetic deformation on morphology and reevaluate potentially diagnostic characters in light of these new data. For example, the ulna of No. mckinleyi is curved whereas the ulna of No. graffami was considered straight, a character originally separating the two species. However, here we present the difference as much more likely related to diagenetic compression in No. graffami rather than as a true biologic difference. Finally, we include copies of three-dimensional surface scans of all major bones for both taxa for reference

Book Review Of Leap Of Faith By Danielle Steel

Leap of Faith is a novel by a famous novelist Danielle Steel. Leap of Faith debuted at the New York Times and is listed as the best-selling novel to fifty-two of Danielle Steel. This novel is about a girl from France, she is Marie-Ange Hawkins who lives in a magnificent castle name, Chateau de Marmouton. At the castle, she has childhood like everyone\u27s dream. She has the freedom, security and abundant affection of both parents and her brother. But when Marie-Ange Hawkins is eleven years old, a tragic accident that befell his parents take her happiness. She becomes an orphan and is sent to America to live with a cruel aunt of her father. Alone in a foreign land, Marie-Ange Hawkins becomes slave of agricultural land by her aunt, only her friendship with Billy and her dream to return to the castle of her childhood memories that make Marie-Ange endures. But the magic happens when Marie-Ange is 21 years old. She makes it back to the castle Chateau de Marmouton again and even get a chance to be the hostess which is the new owner of the castle, Comte Bernard de Beauchamp proposed her. But behind his proposal, Comte Bernard de Beauchamp keeps his hidden bad intentions to Marie-Ange Hawkins. In desperation and uncertainty areas around her, Marie-Ange has to find the faith and courage to take her last step to save her love ones and herself. Danielle Steel packed this book with very interesting by a simple writing style and storyline in the 1800s which is different from the usual. This book is quite interesting and deserves to be read as entertainment by teenagers and adults

\u3cem\u3eNothronychus mckinleyi\u3c/em\u3e Left Ischium

MSM P2117 left ischiumhttps://repository.upenn.edu/vp3d_scans/1023/thumbnail.jp

\u3cem\u3eNothronychus graffami\u3c/em\u3e Proximal Caudal Vertebra

UMNH VP16420 caudal vertebrahttps://repository.upenn.edu/vp3d_scans/1004/thumbnail.jp

Surface Scan of the Squamosal of CPC 274

CPC 274, a new centrosaurine specimen from Mexico, was unearthed in northern Coahuila from 2007-2011. The majority of elements that were found with CPC 274 were surface scanned using a Polhemus FastSCAN system in order to allow readers the ability to manipulate the bones in a 3D environment to assess features directly. The files are .obj files and can be visualized in MeshLabTM, which can be downloaded for free (MeshLab, Visual Computing Lab – ISTI – CNR http://meshlab.sourceforge.net/).https://repository.upenn.edu/vp3d_scans/1031/thumbnail.jp

\u3cem\u3eNothronychus graffami\u3c/em\u3e Tibia

UMNH VP16420 tibiahttps://repository.upenn.edu/vp3d_scans/1014/thumbnail.jp