Bagaceratops

*Bagaceratops rozhdestvenskyi*

* Timothy Bradley Artwork
* Robert F Walters Artwork

***Bagaceratops rozhdestvenskyi*** (meaning "small-horned face") is an extinct genus of small Ceratopsian dinosaur that lived in what is now Mongolia around 80 million years ago, during the Late Cretaceous.

Although emerging late in the reign of the dinosaurs, Bagaceratops had a fairly primitive anatomy and kept the small body size that characterized early ceratopsians; including a tail with neural spines that are longer and are notably thinner; akin to a modern Theropod Spinosaurus.

## History of discovery

The first remains of Bagaceratops were discovered in the Gobi Desert during the 1970s by a joint expedition composed of Mongolian and Polish scientists and it was described in 1975 by two of the expeditions leading scientists, Teresa Maryanska and Halszka Osmólska.

Several of these specimens are now housed at the Paleobiological Institure, Warsaw. ZPAL MgD-I/126, a medium-sized cranium from the Hermiin Tsav, Barun Goyot Formation, is the holotype. The species epithet references Anatoly Konstantinovich Rozhdestvensky. The genus is comprised of 5 full and 20 partial crania, the largest being 17 centimeters long, and represent many ontogenetic stages, with the smallest being 4.7 centimeters long. Thus, its growth stages are relatively well understood. Only fragmentary postcrania are known of the remaining body. Remains once assigned *Protoceratops kozlowskii* and then under *Breviceratops* by Kurzanov (1990) are seen as juvenile *Bagaceratops*. Paul Sereno (2000) showed this by extrapolating.

One skull morphology and size study by Łukasz Czepiński (2019) assigned *Lamaceratops*, *Platyceratops*, *Magnirostris* and *Gobiceratops* as junior synonyms of *Bagaceratops*. The first postcrania were found in 2007 from Hermiin Tsav, and was described by Bitnara Kim et al. (2019). It was catalogued KID196, and is partially-complete. Czepiński (2020) described new specimens of *Bagaceratops* and *Protoceratops* from Üüden Sair and Zamyn Khond, evaluating the implications of them to correlate them to the Djadochta Formation. He considered MPC-D 100/551B as an anagenetic transitionary phase between the two, and is today seen as *Bagaceratops sp. indet.*.

*Bagaceratops*, referencing to Mongolian and Greek, means "small-horned face".

## Description

*Bagaceratops* grew to an adult size of about 1 meter (3.3 ft) long, 50 centimeters (1.6 ft) high, and weighed around 22 kilograms (50 lb). It had a smaller frill (which lacked fenestrae), and only ten grinding teeth per jaw, and more triangular skull than its close relative, *Protoceratops*.

*Bagaceratops* evolved later but retains more primitive characteristics than its earlier relative. Otherwise the two dinosaurs were very similar, each had a beak but no brow horns, and a small horn-like prominence on the snout.

The first remains of *Bagaceratops* were discovered in the Gobi Desert during the 1970s by a joint expedition composed of Mongolian and Polish scientists. Several of these *Bagaceratops* specimens are currently housed in Warsaw, Poland's Paleobiological Institute.

*Bagaceratops* is currently known from five complete and twenty partial crania, the longest of which is 17 cm long. The skulls are spread throughout the life cycle of the animal, with the smallest being only 4.7 cm long, so the growth cycle is relatively well understood. The smaller juvenile skulls were about the same size as a golf ball. Sadly, only fragmentary remains of *Bagaceratops* post-cranial anatomy have been found.

Juvenile remains, initially tentatively named *Protoceratops kozlowskii*, and then renamed *Breviceratops kozlowskii* by Kurzanov in 1990 are now felt to be juvenile *Bagaceratops*. Sereno (2000) explained this by extrapolating that the juvenile *Breviceratops* would grow into a mature *Bagaceratops*.

### *Bagaceratops* Species

The type species, *B. rozhdestvenskyi*, was named in honor of the Russian paleontologist A. K. Rozhdestvensky.

## Classification

Bagaceratops belonged to the Ceratopsian, a group of herbivorous dinosaurs with parrot-like beak which thrived in North America and Asia during the Cretaceous period, which ended roughly 66 million years ago.

## Diet

*Bagaceratops*, like all ceratopsians, was a herbivore. During the Cretaceous, flowering plants were "geographically limited on the landscape", and so it is likely that this dinosaur fed on the predominant plants of the era: ferns, cycads and conifers. It would have used its sharp ceratopsian beak to bite off the leaves or needles.

## JPInstitute.com Description

Bagaceratops was a very small member of the ceratopsian (horn faced) family of dinosaurs. It looked very much like its better-known relative, Protoceratops, except for the head. Unlike its cousin, Bagaceratops' head was shaped almost like a perfect triangle and it had a very small frill.

This basal member of the ceratopsian family had no brow horns, but it did have a well-developed beak with cheek teeth that were perfectly suited for grinding coarse plants. Scientists have collected five complete skulls and almost 20 partial skulls, as well as many skeletal bones. These fossils represent different stages of growth, so scientists have a fairly complete understanding of Bagaceratops' life cycle.

An interesting fact is that, although Bagaceratops came along millions of years later than Protoceratops, Bagaceratops is considered a more primitive creature.

## Links

http://web.archive.org/web/20031008030615/http://www.jpinstitute.com/dinopedia/dinocards/dc\_bagac.html

## References

1. ↑ http://www.palaeontologia.pan.pl/Archive/1975-33\_133-181\_36-50.pdf
2. ↑ https://palaeo-electronica.org/content/2021/3219-the-ecology-of-spinosaurus
3. ↑ http://www.app.pan.pl/article/item/app007012019.html
4. ↑ https://en.wikipedia.org/wiki/Bagaceratops
5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 "Bagaceratops." In: Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. *The Age of Dinosaurs*. Publications International, LTD. p. 132. ISBN 0-7853-0443-6.