Wendiceratops

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Wendiceratops
Artistic reconstruction of the head of Wendiceratops pinhornensis.  Illustration by Danielle Dufault from Evans & Ryan, 2015 [1]

Artistic reconstruction of the head of Wendiceratops pinhornensis . Illustration by Danielle Dufault from Evans & Ryan, 2015

Temporal occurrence
Medium Campanium
78 to 79 million years
Locations
Systematics
Dinosaur (dinosauria)
Pelvic dinosaur (Ornithischia)
Ceratopsia
Ceratopsidae
Centrosaurinae
Wendiceratops
Scientific name
Wendiceratops
Evans & Ryan , 2015
Art
  • Wendiceratops pinhornensis

Wendiceratops is a genus of ceratopsid dinosaurs from the Centrosaurinae group . The only known species of the so far monotypical genus is Wendiceratops pinhornensis from the middle Campanium (approx. 78 to 79 million years ago) of Alberta (Canada).

Etymology and history of research

The generic name honors the Canadian fossil collector Wendy Sloboda in combination with the ending " -ceratops ", which is often used by representatives of the Ceratopsidae , after ancient Greek κέρας kéras "horn" and ὤψ ōps "eye", "face". The additional species " pinhornensis " refers to the location in the Pinhorn Provincial Grazing Reserve , a partially protected public grazing area in southern Alberta (Canada), directly on the border with Montana (USA). The pasture reserve takes its name from the nearby, old post and border station Pinhorn, which in turn owes its name to a certain "Doc Pinhorn", a former veterinarian of the Royal North West Mounted Police . The species name can roughly be translated as "Wendy's horn face from Pinhorn".

The bonebed with the remains of Wendiceratops was discovered by Wendy Sloboda in 2010 . After obtaining the appropriate permits, a team from the Royal Tyrrell Museum of Palaeontology (TMP) in Drumheller (Alberta, Canada) carried out excavations at the site from 2011 to 2014 , with the 2012 excavation season mainly being used to remove overlying rock to expose a larger area of ​​the bonebed. The finds were prepared between 2012 and 2015 at the Royal Ontario Museum (ROM) in Toronto (Ontario, Canada), but are cataloged at the TMP and are also kept there. The first description of the genus and type species was carried out in 2015 by Evans and Ryan .

Fossil record

Skeletal reconstruction of Wendiceratops pinhornensis . Skeletal elements preserved from fossils are highlighted in blue. From Evans & Ryan, 2015

All known remains of Wendiceratops come from a single layer of bone (unofficially known as the "South Side Ceratopsian Bonebed") in the Oldman Formation within the Judith River Group . Wendiceratops is the fourth representative of the Centrosaurinae from the Oldman formation after Albertaceratops , Coronosaurus and Centrosaurus and is likely to have lived in the same region essentially at the same time as Albertaceratops . The respective find layers of Wendiceratops and Albertaceratops occupy a similar stratigraphic position within the lower Oldman Formation and the two sites are only about 3 km apart. The Coronosaurus and Centrosaurus finds, on the other hand, come from stratigraphically higher proportions of the Oldman Formation and are accordingly somewhat younger.

The "South Side Ceratopsian Bonebed", which is only about 40 cm thick, revealed in the course of the excavations 221 individual bone remains of vertebrates, most of which were assigned to Wendiceratops ("monodominant bonebed"). The Wendiceratops residues come from at least 4 individuals, including at least 1 young animal. The holotype (TMP 2011.051.0009) was defined as a right branch (ramus) of the part of the neck shield belonging to the parietal bone (parietal), which has the most essential genus-typical features.

Two isolated teeth of a carnivorous theropod from the family of the Tyrannosauridae and another fragment of a limb bone of a theropod that cannot be identified more precisely are named as additional finds from the "South Side Ceratopsian Bonebed" . In addition, there are 3 fragments of turtle shells, the fragment of a crocodile's horn scale as well as several individual scales and a skull fragment of a representative of the fish-like species . The bonebed also contained numerous shells of mussels and snails, charred plant remains and several pieces of amber .

Characteristics of the genus

Holotype (AC) of Wendiceratops pinhornensis ; "Ep 1" to "ep 5" designate the epiparietals, "sq c" the contact with the scaly bone portion of the neck shield. From Evans & Ryan, 2015
Reconstruction drawing of the neck shield of Wendiceratops pinhornensis (A) in comparison with some other representatives of the Centrosaurinae (B – I). From Evans & Ryan, 2015

Wendiceratops differs from all other representatives of the Centrosaurinae in particular by the shape of the neck shield. Characteristics typical of the genus ( autapomorphies ) are:

  • The epiparietals "ep 1" to "ep 3" are pachyostotically thickened, with a broad base and strongly curved outwards and forwards ("anterodorsal") so that they overlap the outer frame of the pair of windows in the neck shield. In related forms, this feature is limited to the epiparietal "ep 1".
  • An epiparietal "ep 0" located centrally on the outside of the neck shield, as in the closely related genus Sinoceratops , is not present in Wendiceratops .
  • Spike-like elongated epiparietals, as in some other genera of the Centrosaurinae , are also absent.
  • The closely related genus Sinoceratops also has typical, outwardly protruding humps on the outer frame of the pair of windows in the neck shield, immediately below the individual epiparietals. This feature is not present in Wendiceratops .

And apart from the neck shield:

  • The bone process for the nasal horn sits upright on the nasal bone .
  • The ischium of the pelvis shows at the rear end, in a side view, a widened, almost rectangular outline.

All other established skeletal features correspond to those of a typical representative of the Centrosaurinae and prove that they belong to this group. Wendiceratops pinhornensis probably reached a length of 6 m with a body mass of over a ton.

Age classification of the finds

The Oldman Formation in Alberta can be largely equated with the Judith River Formation in Montana (not to be confused with the parent Judith River Group ). For the Judith River Formation, geochronological age data are available for two bentonite horizons in the horizontal and hanging walls of the formation, indicating an age of 79.0 and 78.7 million years, respectively. The authors give the age of the "South Side Ceratopsian Bonebed" accordingly to be around 78 to 79 million years, which would correspond to a relatively short period of time within the middle Campanian .

Systematics and phylogeny

  Ceratopsidae  

 Chasmosaurinae


  Centrosaurinae  

 Diabloceratops


   


 Nasutoceratops


   

 Avaceratops



   

 Xenoceratops


   

 Albertaceratops


   

 Wendiceratops


   

 Sinoceratops



   



 Coronosaurus


   

 Centrosaurus


   

 Spinops




   

 Rubeosaurus


   

 Styracosaurus




   

 Einiosaurus


   

 Achelousaurus


   

 Pachyrhinosaurus





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Systematic position of Wendiceratops according to Evans & Ryan, 2015.

Wendiceratops is valued as a basic representative of the Centrosaurinae due to the age classification and the characteristics typical of the genus . After a strictly parsimonious comparison of the skeletal features, Wendiceratops shows a closer relationship to the genus Sinoceratops, which lives a little later in today's China, than to the genus Albertaceratops, which lives in the same area at the same time .

The nasal horn of Wendiceratops is of particular importance in this context . The existing fossil material, even if only in fragments, indicates that Wendiceratops had a very pronounced nasal horn. This feature is only very weakly pronounced in other basal representatives of the Centrosaurinae. A pronounced nasal horn therefore seems to have developed twice within the group of Ceratopsidae, independently of one another, on the one hand in the Centrosaurinae and on the other hand in the Chasmosaurinae .

Paleecology

Wendiceratops was, like all representatives of the Ceratopsidae, a pure herbivore.

The Western Interior Seaway during the Middle Cretaceous about 100 million years ago

The North American continent was partially covered by a shallow epicontinental sea during the Middle and Upper Cretaceous Period . This Western Interior Seaway divided the continent into two land masses; the western Laramidia and the eastern Appalachia . The latter was temporarily split into a northern and a southern part by another inlet (Hudson Seaway). The sediments of the Judith River Group were deposited as erosion material in the young Rocky Mountains on the east coast of Laramidia, i.e. in the direction of the Western Interior Seaway, whereby alternating terrestrial and marine influences became noticeable due to fluctuating sea levels.

The deeper parts of the Oldman Formation, from which the “South Side Ceratopsian Bonebed” originates, were deposited in a phase with a retreating coastline ( regression ). The area corresponded to a wide, flat coastal plain. Directly on the coast dominated fresh and brackish water swamps in which coal deposits often formed ("foremost formation"). The drier areas further inland were characterized by rivers and their flood plains (Oldman formation).

The matrix of the "South Side Ceratopsian Bonebed" consists of a clayey-sandy siltstone with numerous organic residues. Frequent, charred traces of a root penetration indicate a water-saturated, anoxic moist soil . The bones of Wendiceratops show traces of a corresponding rotting. The matrix of the "South Side Ceratopsian Bonebed" shows no signs of internal stratification or lamination . Accordingly, the bonebed was either deposited as part of a single event or later reworked by dinoturbation , or both is the case. In fact, several of the bones found show evidence of such “trampling”; some of them had stepped so deep into the soft ground that they were stuck upright in the sediment. Most of the bones found, however, lay largely parallel to the stratification in the sediment and a slight preferential orientation of the longitudinal axes indicates an at least small-scale relocation of the bone remnants.

Others

The excavation work on the "South Side Ceratopsian Bonebed" was temporarily accompanied by a camera team. The footage was included in the Canadian mini television series "Dino Hunt Canada". The corresponding episode 1 ("The Horned Dinosaur Mysteries") was first broadcast in January 2015 on the History Channel.

Individual evidence

  1. a b c d e f g h i j k l m n D. C. Evans & MJ Ryan: Cranial Anatomy of Wendiceratops pinhornensis gen. Et sp. nov., a Centrosaurine Ceratopsid (Dinosauria: Ornithischia) from the Oldman Formation (Campanian), Alberta, Canada, and the Evolution of Ceratopsid Nasal Ornamentation. PLOS ONE 10 (7): e0130007. doi : 10.1371 / journal.pone.0130007
  2. Alberta Forestry, Lands and Wildlife: Grazing Reserves - Southern , p. 6, Alberta Forestry, Lands and Wildlife, Edmonton, 1987. (digitized)
  3. ^ A b Royal Ontario Museum: Introducing Wendiceratops: A remarkable new horned dinosaur - Website of the Royal Ontario Museum .
  4. TM Cullen, F. Fanti, Ch. Capobianco, MJ Ryan & DC Evans: A vertebrate microsite from a marine-terrestrial transition in the Foremost Formation (Campanian) of Alberta, Canada, and the use of faunal assemblage data as a paleoenvironmental indicator . In: Palaeogeography, Palaeoclimatology, Palaeoecology , Vol. 444, pp. 101–114, 2016. (digitized version )
  5. TM Cullen & DC Evans: Palaeoenvironmental drivers of vertebrate community composition in the Belly River Group (Campanian) of Alberta, Canada, with implications for dinosaur biogeography. In: BioMed Central Ecology , Vol. 16, No. 52, pp. 1–35, 2016. (online)

Web links

Commons : Wendiceratops  - collection of images, videos and audio files

Introducing Wendiceratops: A remarkable new horned dinosaur - Website of the Royal Ontario Museum with additional image and video material