Spinops
| Spinops | ||||||||||||
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Spinops sternbergorum ; Reconstruction of the skull based on the known skeletal elements |
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| Medium Campanium | ||||||||||||
| 77.5 to 75 million years | ||||||||||||
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| Scientific name | ||||||||||||
| Spinops | ||||||||||||
| Farke , Ryan , Barrett , Tanke , Braman , Loewen & Graham , 2011 | ||||||||||||
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Spinops is a genus of ceratopsid dinosaurs from the Centrosaurinae group . The only known species of the so far monotypical genus is Spinops sternbergorum from the Middle Campanium of Alberta (Canada).
Etymology and history of research
The generic name is composed of the Latin " spina " ("backbone", "thorn") and the ancient Greek ὤψ (" ōps ": "eye", "face"). The additional species " sternbergorum " (" -orum ": genitive , plural ) honors the American fossil collector Charles H. Sternberg and his son Levi Sternberg , who found the original fossils in the summer of 1916. The species name can therefore be roughly translated as “the face of the thorns of the Sternbergs”.
The Sternbergs, a family of commercial fossil collectors, had been recruited by the Geological Survey of Canada (GSC) in 1912 to compete with Barnum Brown , who delivered his Canadian finds to the American Museum of Natural History (AMNH) in New York that at least some of Alberta's rich dinosaur finds remained in their own country. From 1913 to 1915, the family successfully spent the digging season on the Red Deer River in southern Alberta, in an area now known as Dinosaur Provincial Park . After the outbreak of the First World War , the GSC was unable to raise funds for further excavation campaigns from 1916.
At the end of May 1916, shortly before the start of the excavation season, Charles H. Sternberg and his youngest son Levi therefore left the GSC and let the British Museum (Natural History) (BMNH), now the Natural History Museum (NHMUK) in London, be free Recruit employees . Arthur Smith Woodward , then curator of the BMNH's geological department, still had access to funds from the Percy Sladen Foundation. The Sternbergs received $ 2,000 from the foundation as an advance to finance the first two months of the field work and a further $ 2,000 was promised to be paid for the remaining two months of the excavation season if they could provide fossils suitable for the museum.
The Sternbergs immediately went back to the Red Deer River. The success was inevitable and it was not long before the first batch of fossils could be shipped to London. They included material from one was Ceratopsia - bonebed that a previously unknown species from the closer relationship of the opinion of Charles H. Sternberg Styracosaurus represented.
Despite the raging submarine and cruiser warfare in the Atlantic , this first delivery reached London unscathed. In letters to the BMNH, further, even more spectacular finds, including three or four skeletons of hadrosaurs, some with skin prints, were announced for a second delivery to London. This second delivery was part of the cargo of the SS Mount Temple and was never supposed to reach London. On December 6, 1916, the "Mount Temple" was stopped by the German auxiliary cruiser "SMS Möve" in the middle of the crossing and asked to surrender. Although the "Mount Temple" as a cargo ship was only equipped with a single small-caliber gun, she opened fire on the heavily armed enemy auxiliary cruiser. The "Möve" returned the fire and the "Mount Temple" had to surrender. Three crew members of the "Mount Temple" paid for the short battle with their lives; several others were wounded. The survivors were taken on board the “Möve” and finally brought to Germany with the “SS Yarrowdale”, which was captured shortly afterwards. The "Mount Temple" was sunk with its cargo.
This loss was a bitter blow for the Sternbergs, which almost drove them to financial ruin because the outstanding fee was initially not paid. In addition, Woodward was very dissatisfied with the documentary material of the first delivery and disparaged it with the comment "nothing but rubbish". The Sternbergs later received their fee, but the BMNH was no longer interested in further business relationships. In 1931, William Dickson Lang , one of Woodward's successors at the museum, wrote a brief internal note stating that Charles H. Sternberg had repeatedly received offers and that there was no need to respond.
So it is hardly surprising that the fossils of the first batch found their way into the archives of the BMNH without detailed assessment and preparation, where they gathered dust for decades without being noticed. Although the Canadian vertebrate paleontologist Philip J. Currie had become aware of the fossils in the 1980s and took a photo of a parietal bone , a further review by Michael J. Ryan in the museum's extensive archive was inconclusive. It was not until 2004 that Andrew A. Farke noticed the parietal bone fragment again, rather by chance, on the sidelines of the filming of the documentary film " The Truth About Killer Dinosaurs ". He reported it to Ryan, who identified it as the fossil he had been searching for in vain. The two reached out to Paul M. Barrett , curator of the Natural History Museum's dinosaur collection, who arranged for the Sternberg fossils to be fully uncovered. It turned out that the Sternbergs were right from the start; the fossils actually represented a previously unknown species from the family of Styracosaurus .
The first description of Spinops sternbergorum was by Andrew A. Farke, Michael J. Ryan, Paul M. Barrett, Darren H. Tanke , Mark A. Loewen and Mark R. Graham . It was published online on December 6, 2011, 95 years to the day after the sinking of the "SS Mount Temple".
Fossil evidence and age classification of the finds
The previously known fossil material of Spinops sternbergorum includes two partially preserved parietal bones (NHMUK R16307 and NHMUK R16308), a scaly bone (NHMUK R16309), a skull fragment without a neck shield (NHMUK R16306), a fragment of the toothed lower jaw (dentals) and several, unidentifiable ones , Fragments of the postcranial skeleton. One of the two parietal bones (NHMUK R16307) with the most diagnostically significant features was determined as the holotype .
No detailed field records of this find are known from the Sternbergs. The information on the location and stratigraphic position of the site from the received correspondence between the Sternbergs and the BMNH provide conflicting results. In the final preparation of the fossils, however, there was sufficient material from the rock matrix for a pollen analysis . In combination with the information about the location of the Sternberg, the stratigraphic level of the find could be narrowed down to the most hanging parts of the Oldman Formation or the most recumbent parts of the Dinosaur Park Formation within the Belly River group .
This classification corresponds to an age of about 77.5 - 75 Ma and falls accordingly into the Middle Campanium.
features
Spinops sternbergorum differs from all other representatives of the Centrosaurinae in particular through the special shape of the neck shield. The Epiparietalia P1 are the parietal bone, similar to Centrosaurus hook-shaped bent forward over the neck shield. The long, spiky epiparietals in position P2, however, protrude backwards, similar to Styracosaurus , but are also slightly curved upwards.
The cones of the ocular horns are short and directed upwards. The cone of the nasal horn is, in comparison, much longer and slightly curved backwards. These and other features of the cranial skeleton identify Spinops sternbergorum as a representative of the Centrosaurinae.
Gregory S. Paul mentions a length of 4.5 m and a body mass of 1.3 tons for Spinops , but does not give any information on how these data were determined.
Systematics
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| Systematic position of Spinops according to Evans & Ryan, 2015; added after Ryan et al., 2017. |
Charles H. Sternberg originally suspected a close relative of Styracosaurus in his find . The first descriptors of Spinops found the genus in a first phylogenetic analysis in a common clade with Styracosaurus and Centrosaurus .
A later analysis published in the context of the first description of Wendiceratops , however, showed Spinops as the sister taxon of Centrosaurus in a common partial clade with Coronosaurus . Styracosaurus and Rubeosaurus , on the other hand, form a second partial clade.
In 2017 Ryan and co-authors combined the two partial clades with the genera Coronosaurus , Centrosaurus , Spinops , Rubeosaurus and Styracosaurus in an independent taxon ( Centrosaurini ) and compared them to a sister group with the genera Einiosaurus , Achelousaurus and Pachyrhinosaurus ( Pachyrhinosaurini ). The Centrosaurini taxon was defined as all representatives of the Centrosaurinae, which are more closely related to Centrosaurus apertus than to Pachyrhinosaurus canadensis . The group is characterized by heavily ornamented neck shields, a long nasal horn and short over-eye horns.
The results of these two analyzes are shown in simplified form in the cladogram opposite .
Paleecology
Like all representatives of the Ceratopsidae, Spinops was probably a pure herbivore.
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 Belly River group were deposited as erosion material of 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 higher parts of the Oldman Formation and the overlying Dinosaur Park Formation were deposited during a phase of rising sea levels ( transgression ). The area corresponded to a wide, flat coastal plain. The sediments of the Dinosaur Park Formation represent the deposition area directly on the coast, while the sediments of the Oldman Formation were deposited a little further inland, in the area of rivers and their flood plains.
The climate of these deposits can be described as warm-temperate with distinct seasons, but largely frost-free or low-frost winters. In the area of rivers and swamps, forests dominated by conifers grew . Tree-shaped flowering plants have not yet been detected. The undergrowth was made up of ferns , tree ferns , and bedsped plants, while the ground itself was overgrown with mosses , lichens , mushrooms , smaller ferns, club moss plants and bedspeeds. In drier areas, away from the swamps and rivers, the vegetation cover was probably less dense.
Individual evidence
- ↑ a b c d e f g h i j k AA Farke, MJ Ryan, PM Barrett, DH Tanke, DR Braman, MA Loewen & MR Graham: A new centrosaurine from the Late Cretaceous of Alberta, Canada, and the evolution of parietal ornamentation in horned dinosaurs. In: Acta Palaeontologica Polonica , Volume 56, Number 4, 2011, pp. 691-702, ( digitized ).
- ↑ a b Ph. J. Currie: History of Research. In: Ph. J. Currie & EB Koppelhus (eds.): Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed , Indiana University Press, 2005, ISBN 0-253-34595-2 , pp. 10-11, ( reading sample ).
- ^ LS Russell: Dinosaur hunting in western Canada. In: Life Sciences Contributions , Volume 70, 1966, p. 20, ( digitized ).
- ^ A b Ch. H. Sternberg: Hunting Dinosaurs in the Badlands of the Red Deer River, Alberta, Canada: A Sequel to: The Life of a Fossil Hunter. The World Company Press, Lawrence (Kansas), 1917, p. 200, ( digitized ).
- ^ A b c R. Black: Charles H. Sternberg's Lost Dinosaurs. In: Smithsonian Magazine . January 9, 2012, accessed May 15, 2019 . .
- ↑ DH Tanke: Dinosaurs in the deep: the sinking of the SS Mount Temple and related military histories. In: H. Allen (ed.): Alberta Palaeontological Society, Seventh Annual Symposium, Abstracts Volume , Mount Royal College, Calgary, Alberta, 2003, pp. 62-77, ( digitized ).
- ^ A b R. Black: Spinops: The Long-Lost Dinosaur. In: Smithsonian Magazine . December 7, 2011, accessed June 7, 2019 . .
- ^ A b DW Fowler: Revised geochronology, correlation, and dinosaur stratigraphic ranges of the Santonian-Maastrichtian (Late Cretaceous) formations of the Western Interior of North America. In: PLOS ONE , Volume 12, Number 11, 2017, e0188426, doi : 10.1371 / journal.pone.0188426 ( stratigraphic table ).
- ↑ L. Maiorino, AA Farke, T. Kotsakis & P. Piras: Macroevolutionary patterns in cranial and lower jaw shape of ceratopsian dinosaurs (Dinosauria, Ornithischia): phylogeny, morphological integration, and evolutionary rates. In: Evolutionary Ecology Research , Volume 18, 2017, pp. 123-167, ( digitized version ).
- ^ GS Paul: The Princeton Field Guide to Dinosaurs. 2nd edition, Princeton University Press, 2016, ISBN 978-0-691-16766-4 , p. 289, ( reading sample ).
- ↑ a b c DC 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. In: PLOS ONE , Volume 10, Number 7, 2015, e0130007, doi : 10.1371 / journal.pone.0130007 .
- ↑ a b c d MJ Ryan, R. Holmes, J. Mallon, M. Loewen & DC Evans: A basal ceratopsid (Centrosaurinae: Nasutoceratopsini) from the Oldman Formation (Campanian) of Alberta, Canada. In: Canadian Journal of Earth Sciences , Volume 54, Number 1, 2017, pp. 1–14, ( digitized version ).
- ^ Th. M. 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 , Volume 16, Number 52, 2016, doi : 10.1186 / s12898-016-0106-8 .
- ^ DR Braman & EB Koppelhus: Campanian Palynomorphs. In: Ph. J. Currie & EB Koppelhus (eds.): Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed , Indiana University Press, 2005, ISBN 0-253-34595-2 , pp. 101-130, ( reading sample ).
