Abstract Protoceratops was a sheep-sized, quadrupedal dinosaur that lived during the Campanian

Transcription

1 Hope 1 Trevor Hope Dr. William Parker Trilobites to T. rex December 5, 2015 Dinosaur Paper (Protoceratops) Abstract Protoceratops was a sheep-sized, quadrupedal dinosaur that lived during the Campanian stage of the Late Cretaceous period (Maiorino, Farke, Kotsakis, & Piras, 2015). It is distinguished by its prominent neck frill and proportionally large head (Tereschenko, 2008). Protoceratops is suggested to display sexual dimorphism, due to varying frill sizes and skull structures (Lucas, 2007). It is often considered a prey of the Velociraptor, due to skeletal findings in the Gobi Desert region (Hone, Choiniere, Sullivan, Xu, Pittman & Tan 2010). Protoceratops is also portrayed as a nocturnal dinosaur that foraged vegetation at night, with aid from its large orbitals (Ryan, M., J., Chinnery-Allgeier, B., and Ebeth, D. 2010). Introduction Protoceratops is considered to be a member of the Ceratopsia, or horned dinosaurs (Maiorino et. al., 2015). It lived during the Campanian stage of the late Cretaceous period and is generally found in the Djadokhta rock formation outcrops of the Gobi Desert (Maiorino et. al., 2015). Protoceratops, though lacking the typical large nose and eye horns of Ceratopians, was a predecessor to the more familiar horned dinosaur, Triceratops. (Editors, Encylopedia Brittanica Inc., 2015). Protoceratops is a relatively small quadrupedal dinosaur that measures approximately one meter tall and less than three meters in total body length. It is characterized by a proportionally large head, large eyes, and having a prominent neck frill projecting from the back of the skull (Tereschenko, 2008). Sexual dimorphism between the male and female

2 Hope 2 Protoceratops is implied due to two different skulls structures, identified by the height of the frill and the prominent bump on the snout (Maiorino et al., 2015). Protoceratops is hypothesized to be a gregarious, herbivorous animal (Lucas, 2007) that used its adapted large eyes to forage for vegetation at night, to avoid hot temperatures during the day-time in the arid desert climate (Ryan, M. et. al., 2010). The name Protoceratops has a Greek origin; proto meaning first, cerat meaning horn and ops meaning face (Liddell & Scott, 1980). Discussion GEOLOGIC RANGE/GEOGRAPHY Ceratopsia lived through the Late Jurassic to the Late Cretaceous period (Dodson, 2013). Specifically, Protoceratops lived during the Campanian stage of the late Cretaceous period (Dodson, 2013) and are typically found in the Campanian-aged Djadokhta formation outcrops of the Gobi Desert in Southern Mongolia (Maiorino et. al., 2015). PHYLOGENY Protoceratops is a member of the family of Protoceratopsidae, which are dinosaurs that are generally considered to be smaller and more primitive than later Ceratopsidae (Maiorino et al., 2015). Protoceratops is considered to be a member of the Ceratopsia, or horned dinosaurs (Farke, 2010). Ceratopsia are characterized as a group of herbivorous, ornithischian dinosaurs that included a large amount of cranial, nasal, and brow horn variability (Farke, 2010). Protoceratops is a descendent of Triceratops, which is considerably the most well-known Ceratopsian. Ceratopsians have a rostral bone in the skull, a narrow beak and flaring jugals (cheeks), a deep jugal with a distinct ridge, and a palate in the front of their mouth with a

3 Hope 3 complex battery of replacement teeth (Lucas, 2007). The jaws were beak-like and teeth were present in both upper and lower jaws. PHYSICAL CHARACTERISTICS Protoceratops was first discovered in Mongolia, by Walter Granger and W.K Gregory in 1923 (Dodson, 2013). Roy Chapman Andrews led the early expedition looking for human ancestors, but instead found remains of multiple dinosaurs. The discovery of Protoceratops skeletal fossils amongst those collected were given the species name by Granger and Gregory P. andrewsi to honor Andrews. Researchers immediately noted the importance of the Protoceratops finds, and the Genus was hailed as the long-sought ancestor of Triceratops (Maiorino et al., 2015). The fossils were in an excellent state of preservation, with even the sclerotic rings preserved in some specimens (Dodson, P. 1996). Since then, more than one hundred well-preserved skulls and skeletons have been found providing information on ontogeny and variability within Protoceratops (Maiorino et al., 2015). Protoceratops was a small, less than three meters in total body length, one meter tall, quadrupedal dinosaur (Tereschenko, 2008). A full grown adult is estimated to be less than fourhundred pounds in body weight (Tereschenko, 2008). Protoceratops had a proportionally large skull (see figure 1). The skull was nearly 1/5 the total body length. (Editors of Encyclopedia Brittanica, 2015). Protoceratops had four pairs of fenestrae (skull openings) and had a considerably smaller naris than seen in later genera (Maiorino et al., 2015). It also had large orbits (eye holes) that measured fifty millimeters in diameter (Maiorino et al., 2015). Protoceratops also had a smaller fenestrae behind the eyes, which is called the infratemporal fenestra (Tereschenko, 2008). Protoceratops is characterized by a skull with a thin, bony frill (a shelf of bone projecting from the back of the skull), and lacks prominent horns that are

4 Hope 4 characterized by other Ceratopsids, such as the well-known Triceratops (Tereschenko, 2008). The large neck frill was likely used for display to impress other members of the species (Maiorino et al., 2015). Some researchers have hypothesized that the frill was used for protection. However, since the frill is fragile and offers poor leverage for possible attachment sites of the jaw muscles, the idea is unlikely (Farke, 2010). Protoceratops moved about on four limbs, but the back legs were larger and more developed than the front pair. The spine had a pronounced humped arch due to the differing paired leg sizes. (Editors of Encyclopedia Brittanica, 2015). In 2001, a second species P. hellenikorhinus, was named and also dated back from the Campanian stage of the upper Cretaceous. This was a larger version of the Protoceratops andrewski, with a slightly different frill and larger jugal horns. It also had two horns over the arch bone and no teeth in the front of the snout (Lambert, O, Godefroit, P, Li, H, Schang, C.-Y. & Dong, Z.-M. 2001). LIFE HABITS A significant fossil discovery unearthed in Mongolia in 1965, but re-examined in 2011, showed that the skeleton of Protoceratops was preserved with its own footprint (Gill, Victoria, 2015). (see figure 2).This is the first known example of a dinosaur fossil found in its own footprint. It is generally difficult to match a fossil with a footprint at even the species level. By matching the footprint to the fossil, you can begin to study the tracks and how the animal moved about (Gill, Victoria, 2015). The tracks can tell you a lot about how the dinosaur moved, lived, interacted, fed, etc. But with tracks, you can tell how much it weighed, how it moved, if it was running or walking. You can even tell if it was limping. With tracks you are dealing with living animals. (Gill, Victoria, 2015).

5 Hope 5 Fossil evidence suggests that Protoceratops was a common prey of Velociraptor. In 1971, a fossil was discovered in Mongolia, that displayed a Protoceratops andrewski and a Velociraptor mongoliensis locked in battle (Hone et al., 2010). It is often rare to find fossilized evidence of direct trophic interactions among two taxa (Hone et al., 2010). It is believed that the two dinosaurs were buried during a sandstorm and died simultaneously, during a fight. Velociraptor tooth-marks were found imbedded on the bones of the Protoceratops, indicating that the raptor was feeding on it (Hone et al., 2010). Protoceratops are suggested to be gregarious or herding animal on the basis of the hundreds of skeletons and skulls found together in the Gobi Desert region (Lucas, 2007). They are presumed to have been foragers of the vegetation that grew in the wetter places of the desert, such as intermittent lakes and streams (Lucas, 2007). Fossilized evidence of Protoceratops skulls suggest sexual dimorphism among the species. Sexual dimorphism is a phenotypic differentiation between males and females of the same species (Maiorino et al., 2015). Measurements of the skulls indicate that Protoceratops had skulls of two different shapes as adults (Maiorino et al., 2015). One type of skull had a larger and more pronounced frill than the other type of skull and a more prominent bump on the snout (Lucas, 2007). It is likely hypothesized that these two skull types represent a male and a female of a single species (see figure 3). The remarkable specimen of a nest of Protoceratops andrewski, discovered in 2011, in the Upper Cretaceous Djadokhta formation in Mongolia, implies that parental care and sociality are basal behaviors of Ceratopsians (Fatovsky, D. E., Weishampel, D.B., Watabe, M., Barsbold, R., Tsogtbaatar, K.H., and Narmandakh, P., 2011). The nest found in Mongolia was complete with fifteen juvenile skeletons (Fatovsky et. al., 2011). These juveniles were relatively large and

6 Hope 6 their advanced stage of development suggests that they remained and grew in their nests during the early stages after postnatal development (Fatovsky et. al., 2011). This implies that the Protoceratops mother cared for her young, well after they were born, demonstrating parental care (see figure 4). Many scientists have speculated on the relatively large eyes of Protoceratops. Researchers have studied large sclerotic rings in birds that correlate to ecological habits of visually hunting predation and/or a nocturnal lifestyle (Ryan, M. et. al., 2010). Protoceratops andrewski is characterized by large eyes that are approximately fifty millimeters in diameter. One hypothesis for the reason for its large eyes is that Protoceratops used them for visual predation. However, this hypothesis is highly unlikely because it is inconsistent with other pieces of information, including the morphology of jaws and dentition, tooth-wear, and the relative abundance of Protoceratops (Ryan, M. et. al., 2010). A more likely hypothesis for the large eyes, is that Protoceratops lived a nocturnal lifestyle, possibly helping it avoid the extreme heat of the hot desert environment of the Djadokhta, during the daytime (Ryan, M. et. al., 2010). Protoceratops could have foraged at night, while the air temperature was cool, and sheltered under vegetation/burrows during the day (Ryan, M. et. al., 2010). This would explain the larger eye socket size for a creature that was not understood to be a carnivore. MYTHOLOGICAL BELIEFS Protoceratops has also been linked to a mythological Greek legend, known as the Griffin Legend (Lucas, 2007). The Griffin Legend was a mythical creature that was believed to have existed in western Europe to Eastern India and beyond (Lucas, 2007). The Griffin was portrayed to be royal/regal monster and was associated with guarding deposits of royal gold. It was thought to stand guard over the treasures and lay nests of its eggs nearby (Editors of

7 Hope 7 Protoceratops.org, 2015). The Griffin symbol has been found on many ancient Greek artifacts, which appeared as a mixed creature of an eagle and a lion (see figure 5). Greek writings of the Griffin Legend are thought to have begun around 675 BCE. This timing also correlates with Scythian nomadic activity in those same areas in Central Asia where the Protoceratops fossils, including skeletons, eggs, and nests have been found (Editors of Protoceratops.org, 2015). These myths, while largely fictional, do give some confirmation to the general appearance, egg-nesting nature and geographic territory of the actual Protoceratops species. Conclusion Since it was first discovered in 1923, by Walter Granger and W. K. Gregory, the Protoceratops has become one of the most well-known Ceratopsians, based on the hundreds of skeletal findings in the Djadokhta rock formation outcrops of the Gobi Desert (Maiorino et. al. 2015). Protoceratops is considered to be a member of the Ceratopsia, or horned dinosaurs and is a member of the family Protoceratopsidae, which are dinosaurs that are generally considered to be smaller and more primitive than later Ceratopsidae (Maiorino et. al., 2015). It lived during the Campanian stage of the late Cretaceous period. Protoceratops is a relatively small quadrupedal dinosaur that measures approximately one meter tall and less than three meters in total body length. It is characterized by a proportionally large head, large eyes, and having a prominent neck frill projecting from the back of the skull (Tereschenko, 2008). Sexual dimorphism between the male and female Protoceratops is implied due to two different skulls structures, identified by the height of the frill and the prominent bump on the snout (Maiorino et al., 2015). Based on fossil evidence, it is hypothesized that Protoceratops was a common prey of the Velociraptor mongoliensis. A famous discovery in 1971 showed a Protoceratops andrewski and Velociraptor mongoliensis locked together during a fight. It is presumed that the two specimens

8 Hope 8 were buried in a sandstorm and died simultaneously, preserving their skeletal remains (Hone et al., 2010). It is hypothesized to be a gregarious, herbivorous animal (Lucas, 2007) that used its adapted large eyes to forage for vegetation at night, so as to avoid the extreme heat of the Mongolian desert climate during the day-time (Ryan, M. et. al., 2010) and not an adaption for predatory (carnivorous) behavior.

9 Hope 9 Figure 1: Protoceratops was a small, sheep-sized dinosaur that measured approximately less than a meter tall, and less than three meters in total body length. This image gives an approximate idea as to the size comparison with an average human. ( 2015)

10 Hope 10 Figure 2: Fossil image showing the discovery of the paired footprint and matched skeleton found in 1965 in Mongolia. This is important for studying a specific species tracking and behavioral traits. ( 2011)

11 Hope 11 Figure 3: This image displays the sexual dimorphism theory on the basis of skull size and shape. On the left is a hypothetical male Protoceratops that has a large pronounced frill and prominent bump on the front snout. On the right is the hypothetical female Protoceratops that has a less pronounced head frill and less prominent bump on the snout than the male skull. (Maiorino, L., Farke, A. A., Kotsakis, T., & Piras, P., 2015)

12 Hope 12 Figure 4: This is an image of the 70 million year-old Protoceratops nest that was discovered in 2011 in Mongolia. The nest contains 15 juvenile skeletons of Protoceratops andrewski. This finding supports the hypothesis that Protoceratops gave parental care to its young, well into its post-natal development. (Fatovsky et. al., 2011)

13 Hope 13 Figure 5: This photo shows the Griffin legend on an ancient Greek vase, c.350 BCE. The mythical monster was said to be a mixture of a lion and eagle. ( /p1_legend.php, 2015)

14 Hope 14 References Dodson, P. (1996). Horned Dinosaurs. Priceton University Press, Princeton, NJ. Pp Dodson, P. (2013). Ceratopsia increase: history and trends. Canadian Journal of Earth Sciences, 50(3), 294. Retrieved from 85&v=2.1&u=tall85761&it=r&p=AONE&asid=2a47dd1a9a071a5cc2fd962060b497d6 Editors of Encyclopedia Brittanica. Protoceratops Dinosaur Genus. (Encyclopedia Brittanica Inc., 2015). Retrieved from Editors of Protoceratops.Org. Protoceratops. (Answers 2000 Limited, ). Retrieved from Farke, A. A. (2010). Evolution, homology, and function of the supracranial sinuses in ceratopsian dinosaurs. Journal Of Vertebrate Paleontology, 30(5), Retrieved from a fd95c7a1%40sessionmgr4005&vid=5&hid=4209 Fatovsky, D. E., Weishampel, D.B., Watabe, M., Barsbold, R., Tsogtbaatar, K.H., and Narmandakh P. (2011). A Nest of Protoceratops Andrewski (Dinosauria, Ornithischia). Journal of Paleontology, 85(6), Retrieved from INOSAURIA_ORNITHISCHIA_ Gill, Victoria. Protoceratops Dinosaur Found With Its Own Tracks. (BBC Nature, 2015). Retrieved from Hone, D., Choiniere, J., Sullivan, C., Xu, X., Pittman, M., & Tan, Q. (2010). New evidence for a trophic relationship between the dinosaurs Velociraptor and Protoceratops. Palaeogeography, Palaeoclimatology, Palaeoecology, 291(3/4), Retrieved from

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