Episode 254 is all about Alioramus, a tyrannosaurid from Asia with nearly 80 teeth and 8 small horns on its snout.
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In this episode, we discuss:
News:
- New alvarezsauroid, Shishugounykus inexpectus, was described from China source
- New Saurornitholestes specimens expand what we know about the genus and synonymize source
- Saturnalia skull and jaw bones were CT scanned and help show why its skull was small source
- Darwin and Dinosaurs exhibition opened in Idaho Falls source
- A giant chicken skeleton was installed at the Denver Central Library source
The dinosaur of the day: Alioramus
- Tyrannosaurid that lived in the Late Cretaceous in what is now Asia (mostly Mongolia)
- Bipedal, and had sharp teeth
- Only known from juvenile or sub-adult specimens, so not clear how big it was as an adult
- Kurzanov estimated it to be 16 to 20 ft (5 to 6 m) long, but apparently he didn’t take into account the fact that skulls lengthen/get deformed during fossilization, so may be an overestimate
- Had more teeth than other tyrannosaurids
- Had 76 or 78 teeth, more than other tyrannosaurids
- Had long legs, which is like other young tyrannosaurs (had long legs and could fill a different niche than larger, adult tyrannosaurs)
- Long legs meant it could hunt small, fast prey
- Two species: Alioramus remotus and Alioramus altai
- Type species is Alioramus remotus
- Named in 1976 by Sergei Kurzanov
- Name means “different branch”
- Crest and low skull looked different from other tyrannosaurids, and Kurzanov thought it was not closely related to other members of the family (hence the name “different branch”)
- Not clear how its related to other tyrannosaurids, may be closely related to Tarbosaurus bataar
- Holotype was found in the Gobi Desert (Nogon-Tsav locality)
- Found a partial skull and three footbones (metatarsals) in Mongolia of Alioramus remotus
- Stephen Brusatte and others described a second species, Alioramus altai, in 2009
- Possible third species, Alioramus sinensis, found in 2014 in China
- Alioramus altai holotype found in the Nemegt Formation in Mongolia in a 2001 expedition (Tsaagan Khuushu locality)
- The species name altai refers to the Altai mountain range of southern Mongolia
- Alioramus altai specimen much more complete
- Alioramus altai showed that Alioramus was not a juvenile Tarbosaurus (different from juvenile Tarbosaurus specimens found)
- Alioramus altai specimen was about 9 years old
- Had a long, slender, lower jaw, though could be a juvenile characteristic
- Alioramus remotus skull was about 18 in (45 cm) long, and was long and low, and the nasal bones had five bony crests
- Alioramus altai snout is about 2/3 of the skull length
- Had a thick nuchal crest, the part of the skull where the neck muscles attach (similar to Tarbosaurus and Tyrannosaurus)
- Alioramus altai had at least eight small horns on its face, including two horns below the eyes and a row on top of the nose (adults may have had more ornamentation)
- Unclear why it had crests on its snout
- Alioramus remotus may have also had 8 horns on its skull, but the holotype is too fragmentary to know for sure
- Based on the number of teeth, that were evenly spaced, and the narrow skull, probably didn’t have a strong bite compared to other tyrannosaurs (that had deep, heavy skulls) and could have gone for unarmored prey
- Lived alongside Tarbosaurus (went after different types of prey, also known as niche partioning)
- Could not do the “puncture-pull” style of feeding like large adult tyrannosaurids (with really strong bite forces that could crush bone)
- Tarbosaurus had a short, deep skull
- Lived in a wet, humid climate, possibly with sauropods, pachycephalosaurs, ankylosaurids, and hadrosaurs
Fun Fact: Part of the drive toward big sauropods in the Jurassic may have been because of a “floral turnover” after the End-Triassic extinction.
