Paleo File: Bistahieversor

• Pronunciation: (Bis-Tah-Hee-Ever-Sore)
• Meaning: "Bistahi Destroyer"
• Length: 30ft
• Height: 10ft
• Weight: 1 ton
• Diet: Carnivorous
• Time: 74 MYA
• Region: North America (New Mexico)

Art and Copyright belongs to Robert; SADistiknight on DeviantArt

Bistahieversor, which translates to “Bistahi Destroyer”, comes from the Kirtland Formation of New Mexico. It represents an unusual stage in the evolution of Tyrannosaurs, due to the shape of its head, whole above its eye socket, and slim, yet strong build.

Original Skull Material (Public Domain)

Reconstructed Skull (Public Domain)

Originally found in 1990, the name Bistahieversor never existed in its place existed Aublysodon. However, more material uncovered in 1992, including a partial skeleton and skull, revealed more of the animal’s anatomy enough to differentiate it from the genus Aublysodon. Then, again more material was uncovered in the Bisti wilderness of New Mexico in 1998 to further differentiate it from its initial genus. It was not until 2010 that the animal was renamed Bistahieversor.

Bistahieversor Reconstruction (Art and Copyright belongs to KindEdmarka on DeviantArt)

Bistahieversor contained features of more advanced Tyrannosaurs as well as more derived genus. Its skull was unusually deep in contrast to Tyrannosaurs that appeared later than it and after it, which suggests that the deepness of the skull is not a feature that evolved in advancement of the family but rather a characteristic that evolved due to environmental pressures. Bistahieversor has been placed in the subfamily Tyrannosaurinae, which consists of; Daspletosaurus, Teratophoneus, Lythronax, and Nanuqsaurus. The material is from both adolescent and adult individuals and as such, the growth stage can be roughly inferred, which is different from many other Tyrannosaur genus. The skull holds a whole above the eye socket found only in the adult skulls and was absent in the juvenile skull, which suggests that it only appeared in adulthood. It is thought that the whole would have held an air sac in life to reduce the skull’s weight. Bistahieversor measured an approximate 30 feet long and 10 feet tall, which reached the similar sizes of Daspletosaurus.

(Art and Copyright belongs to Raul Linia)

This find has elucidated a new predator of the southern hemisphere that had not been previously known, and represents a new spot in the ecosystem. Only more finds will help outline the animal’s hunting habits and perhaps give more insight into how the animal lived.

(Art and Copyright belongs to PrehistoricWildlife)

Works Cited:

"Bistahieversor." Bistahieversor. Prehistoricwildlife, n.d. Web. 12 Jan. 2016. 

"Bistahieversor." Wikipedia. Wikimedia Foundation, n.d. Web. 12 Jan. 2016.

Rettner, Rachael. "New Tyrannosaur Species Discovered." LiveScience. TechMedia Network, 28 Jan. 2010. Web. 12 Jan. 2016.

Paleo File: Alioramus

• Pronunciation: (Ah-Lee-Oh-Ram-Us)
• Meaning: "Different Branch"
• Length: 19ft
• Height: 6ft
• Diet: Carnivorous
• Time: Cretaceous (75 MYA)
• Region: Asia (Mongolia)

Alioramus, a midsized tyrannosaur from the Late Cretaceous (72-66MYA) of Mongolia, is yet another dinosaur grounded in mystery due to scant remains. However, even though this is the case, many details about the animal can be extrapolated from the few remains that have been uncovered.

Alioramus Skull Reconstruction

         A Soviet-Mongolian expedition to the Gobi Desert of Mongolia in the early 1970s uncovered the remains of Alioramus, but it was not until 1976 that soviet paleontologist, Sergei Kurzanov, identified the remains. Kurzanov found the animal to be a tyrannosaur and named it Alioramus remotus, which translates to “Removed Other Branch”. Kurzanov named his find after the fact that the animal contained characteristics of no other animal of the family it belonged to. Kurzanov placed the animal in the general superfamily Tyrannosauroidea. Alioramus remained a very partial species with only fragmentary skull material having been found, until another much more complete find was discovered in 2001 by Julia Clarke on another expedition to Mongolia with the American Museum of Natural History and Mongolian Academy of Sciences. This new species was named Altai, in homage to the Altai Mountains in Mongolia in 2009. This new find consisted of a nearly complete skull, missing just a few minor bones, a complete neck, large segments of the back, sacrum, tail, a nearly complete pelvis, and most of the hind limbs. Although still rather fragmentary, the animal can now be rather accurately reconstructed with a proper body.

Alioramus Reconstruction (Art and Copyright belongs to Fred Wierum; FredtheDinosaurman on DeviantArt)

          What is known of Alioramus is scant, but what is known is rather interesting. Alioramus is known only from juvenile specimens, and as such, the adult size cannot be fully determined. However, the juvenile specimens uncovered suggest an length of approximately 15-19ft; juvenile Alioramus would have stood as tall as an adult human. The most distinguishing features of Alioramus is its skull. The animal had a very gracile skull much more elongate than the majority of other known Tyrannosaurs (minus Nanotyrannus), not only this, but the skull sported a series of about 5-6 small hornlets that ran along the snout and jutted upwards about 1-2 inches. Due to the fact that the remains only represent juvenile specimens, scientists had hypothesized that Alioramus might be the juvenile of the larger tyrannosaur that it shared its environment with; Tarbosaurus. However, juvenile specimens identified to belong to the genus Tarbosaurus with differing characteristics to Alioramus suggest that the animal was a different species altogether. Slender features and legs like that of an Ornithomimosaur, suggests that Alioramus would have preyed upon smaller animals in comparison to the much larger and more robust Tarbosaurus.

Alioramus Reconstruction with scale (Art and Copyright belongs to Robinson Kunz; Teratophoneus on DeviantArt)

           Speaking of phylogeny, Alioramus has been placed under its own subfamily, Alioramini, which lies inside the family Tyrannosaurinae. Tyrannosaurinae consists of the later tyrannosaurs that shared the characteristics of a atrophied arms, large skulls, and slender legs. Alioramini’s only other member is the recently discovered Qianzhousaurus. Alioramus is related to the other, more well known, tyrannosaurs like; Albertosaurus, Daspletosaurus, Tarbosaurus, and Tyrannosaurus. The 2001 Alioramus finds found that, although the animal had a thin snout usually characteristic of more basal (primitive) forms, it was more related to the large robust forms seen living in close historical proximity to it; I.E. Tyrannosaurus.

            Mongolia, the region of which Alioramus called home, is home to a vast array of other animals that we know a lot about due to over 30 years of research and discovery in the region. Tarbosaurus, Deinocheirus, Gallimimus, Therizinosaurus, Homalocephale, and Nemegtosaurus all shared the ecosystem with Alioramus.

Works Cited:

"Alioramus." Wikipedia. Wikimedia Foundation, n.d. Web. 30 Dec. 2015. <https://en.wikipedia.org/wiki/Alioramus>.

Switek, Brian. "Alioramus Altai: A New, Multi-Horned Tyrant." Smithsonian. Smithsonian, 6 Oct. 2009. Web. 30 Dec. 2015. <http://www.smithsonianmag.com/science-nature/alioramus-altai-a-new-multi-horned-tyrant-54512057/?no-ist>.

Murray, Melissa. "Australian Museum." Alioramus Altai -. Australian Museum, 20 Nov. 2013. Web. 30 Dec. 2015. <http://australianmuseum.net.au/alioramus-altai>.

Hone, Dave. "Guest Post: A New Tyrannosaur - Alioramus Altai." Dave Hones Archosaur Musings. Word Press, 05 Oct. 2009. Web. 30 Dec. 2015. <https://archosaurmusings.wordpress.com/2009/10/06/guest-post-a-new-tyrannosaur-alioramus-altai/>.