And then there were nine...

The top right species is now synonymous with the top left one.

Up to 15 species of Psittacosaurus have been described in the scientific litterature, but a few are dubious and others have been shown to be synonymous. With the latest 3D geometric morphometric study of the skulls of the three species of Psittacosaurids from the Lujiatun beds of the Yixian Formation of China, this number is now down to nine: Hongshanosaurus houi and Psittacosaurus major are now taxonomically dead...

Psittacosaurus lujiatunensis

Here is the paper and abstract:
Hedrick BP, Dodson P (2013) Lujiatun Psittacosaurids: Understanding Individual and Taphonomic Variation Using 3D Geometric Morphometrics. PLoS ONE 8(8): e69265.

Abstract:

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.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com). Check out my portfolio at spinops.blogspot.com.

Spinops sternbergorum

Fig 1.- Life reconstruction of Spinops sternbergorum.

This dinosaur was “rediscovered” within the precinct of the Natural History Museum in London, almost a century after it was excavated in the Dinosaur Park Formation in Alberta, Canada. It was only very recently realized that the long forgotten skull fragments belong to a new species.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

Fig 2.- Detail.

Reference:

Farke, A.A., Ryan, M.J., Barrett, P.M., Tanke, D.H., Braman, D.R., Loewen, M.A., and Graham, M.R. 2011. A new centrosaurine from the Late Cretaceous of Alberta, Canada, and the evolution of parietal ornamentation in horned dinosaurs. Acta Palaeontologica Polonica 56 (4): 691–702.

Abstract: In 1916, a centrosaurine dinosaur bonebed was excavated within the Campanian−aged deposits of what is now Dinosaur Provincial Park, Alberta, Canada. Specimens from this now−lost quarry, including two parietals, a squamosal, a skull missing the frill, and an incomplete dentary, were purchased by The Natural History Museum, London. The material was recently reprepared and identified herein as a previously unknown taxon, Spinops sternbergorum gen. et sp. nov. Based upon the available locality data and paleopalynology, the quarry lies in either the upper part of the Oldman Formation or the lower part of the Dinosaur Park Formation. The facial region of the partial skull is similar to putative mature specimens of Centrosaurus spp. and Styracosaurus albertensis, with short, rounded postorbital horncores and a large, erect nasal horncore. Parietal ornamentation is consistent on both known parietals and is unique among ceratopsids. Bilateral, procurved parietal hooks occupy the P1 (medial−most) position on the dorsal surface of the parietal and are very similar to those seen in Centrosaurus apertus. Epiparietals in the P2 or possibly P3 position (lateral to P1) manifest as extremely elongate, caudally directed spikes, unlike the condition in C. apertus, S. albertensis, or any other “derived” centrosaurine. Cladistic analysis suggests that S. sternbergorum is closely related to Centrosaurus and Styracosaurus. Historically, based upon the condition in Styracosaurus and related centrosaurines, it was assumed that the medial−most elongated spikes on centrosaurine parietals correspond to the P3 epiparietal position. The exception illustrated in the new taxon suggests that homologies of epiparietals among basal centrosaurines (e.g., Albertaceratops and Diabloceratops) and derived centrosaurines (e.g., Styracosaurus and “pachyrhinosaurs”) should be reconsidered. The medially−placed, caudally−directed “P3” process of basal centrosaurines may, in fact, be homologous with P2.

Pachyrhinosaurus perotorum, new boreal dinosaur from Alaska

Fig 1.- Pachyrhinosaurus perotorum.

 

Anthony R. Fiorillo, and Ronald S. Tykoski, from the Museum of Nature and Science, Dallas, TX, have just described a new species of Ceratopsian (Horned dinosaur), Pachyrhinosaurus perotorum from the Prince Creek formation of the North Slope in the northernmost region of Alaska. The species is based on two fragments of parietals (which in Ceratopsians are the bones that formed the frill) and a partial skull.



What makes P. perotorum special is that it was a boreal dinosaur. During the Late Cretaceous, Alaska was situated at latitudes similar or higher than its current geographical position, meaning that its northern inhabitants experienced, as of today, a yearly 6 month long winter night with freezing temperature. Polar dinosaurs are also known from the southern hemisphere with representatives of the early Cretaceous period such as the hypsilophodont Leallynasaura amicagraphica from Australia featured in WWD. The Late Cretaceous Prince Creek formation of Alaska, however, appears to be the richest trove of polar dinosaur bones from either hemisphere. The Kikak-Tegoseak Quarry where the P. perotorum remains were unearthed, also include bones of the raptors Dromaeosaurus albertensis and Troodon formosus as well as remains attributed to the tyrannosaur Gorgosaurus libratus, some hadrosaurs and the Pachycephalosaur Alaskacephale gangloffi.

Fig 2.- Pachyrhinosaurus canadensis.

P. perotorum is the third named species of the genus Pachyrhinosaurus which contains Ceratopsians with massive flattened bosses in place of the usual horns on the nose and above the eyes. The larger 6 meter long P. canadensis was described in 1950. It is known from the St Mary River (Upper Campanian-Lower Maastrichtian) and Horseshoe Canyon Formations (Lower Maastrichtian) of Alberta, Canada. The smaller 5 meter long P. lakustai, described in 2008 from the Wapiti Formation (Late Campanian) of Alberta, differs from P. canadensis by well-separated nasal and supraorbital bosses and by the presence of a comb of horns on the parietal bone just behind the eyes.

 

Fig 3.- Pachyrhinosaurus lakustai.

P. perotorum is the youngest (Lower Maastrichtian) of the three species, and about the same size as P. lakustai. It is characterized by the unique anterior parietal pair of horns just at the top edge of the parietal cavities (the large holes in the frill), and a narrow dome in a back portion of the nasal boss. The bizarre blunt rounded rostrum might just be an individual oddity (the partial skull is apparently from an aged individual). A recently discovered specimen numbered TMP 2002.76.1 (Housed at the Royal Tyrrel Museum), from the Dinosaur Park Formation, Alberta, which shows similarities with both Pachyrhinosaurus and Achelousaurus, might represent a fourth species.


Pachyrhinosaurus belongs to the Pachyrhinosauri tribe of the Centrosaurine Ceratopsian that also contains the basal genera with enlarged nasal horns Einiosaurus and Rubeosaurus, as well as the derived forms with nasal and supraorbital bosses, Achelousaurus.


Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

 

References:

 

P. J. Currie, W. Langston, and D. H. Tanke. 2008. A new species of Pachyrhinosaurus (Dinosauria, Ceratopsidae) from the Upper Cretaceous of Alberta, Canada. In P. J. Currie, W. Langston Jr., D. H. Tanke (eds.), in A New Horned Dinosaur from an Upper Cretaceous Bone Bed in Alberta. NRC Research Press, Ottawa 1-108.

A.R. Fiorillo, and R.S.T. Tykoski, R.S.T.  2011. A new species of the centrosaurine ceratopsid Pachyrhinosaurus from the North Slope (Prince Creek Formation: Maastrichtian) of Alaska. Acta Palaeontologica Polonica. In press.

Nasutuceratops titusi, a new ceratopsian from Utah

The Kaiparowits Formation of Late Cretaceous Campanian age, in the Grand Staircase-Escalante National Monument, Southern Utah, has in recent years released a number of spectacular finds, including the ceratopsians Utahceratops and Kosmoceratops and the tyrannosaurid Teratophoneus.

This year sensation from Utah might well be another ceratopsian, Nasutuceratops titusi, known from an almost complete skull and an associated left forelimb, as well as skull fragments from two other individuals. Some skin impressions were also found with the forelimb. Nasutuceratops is still a nomen nudum (“naked name”), meaning it has not been officially and formally described in a published scientific journal yet. It has been named by Eric Karl Lund (advisor: Scott Sampson) in his Master of Science Geology thesis submitted to the faculty of the University of Utah in 2010. In a comprehensive phylogenetical analysis, this short snouted long horned centrosaurine ceratopsian was found to be closely related to the contemporary Avaceratops lammersi from Montana.

To my knowledge, the talented paleoartist Andrey Atuchin is the first one to have made a reconstruction of this intriguing animal. Mine is far from being as good as his but here it is nevertheless.

Update: it has been officially described in 2013 as Nasutoceratops titusi by Sampson et al (with an "o" instead of a "u").

Ref: Sampson, S. D., Lund, E. K., Loewen, M. A., Farke, A. A, Clayton, K. E. 2013. A remarkable short-snouted horned dinosaur from the Late Cretaceous (late Campanian) of southern Laramidia. Proceedings of the Royal Society B: Biological Sciences 280 (1766) 20131186.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission.