Episode 346 is all about Abydosaurus, an Early Cretaceous brachiosaurid that is known from multiple complete skulls.
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In this episode, we discuss:
News:
- A new Heterodontosaurus shows the first full set of gastralia ever found on an Ornithischian source
- Triassic fossils were found in a new creek bed site in Virginia source
- A new cretaceous ornithopod vertebra was found in Oregon source
- Roper Mountain Science Center in South Carolina has an exhibit called Be The Dinosaur this summer source
- A Triceratops replica is on display at the Waynesboro, Virginia Public Library source
- “Dinny” the 110 tonne Brontosaurus at the Calgary Zoo is getting repaired source
- The Science Museum of Minnesota is working on getting Minnesota an official state fossil source
The dinosaur of the day: Abydosaurus
- Brachiosaurid sauropod that lived in the Early Cretaceous in what is now Utah, United States (Cedar Mountain Formation)
- Sauropod, so had a small head, long neck and tail, and large body (walked on four, columnar legs)
- In 2012, Thomas Holtz estimated Abydosaurus to be about 60 ft (18.3 m) long
- Holotype is DINO 16488, and includes a nearly complete skull, lower jaws, and the first four neck vertebrae
- Found about 1200 ft away from the Carnegie Quarry (Late Jurassic )
- BYU students and faculty used jackhammers and concrete saws to excavate, and at one point a crew came in and used explosives to blast away some of the rock (it was embedded in tough sandstone)
- Lots of skulls found (4)
- All four skulls were from juveniles
- First time a complete sauropod skull from the Cretaceous has been found in the Western Hemisphere (the Americas)
- At the time Abydosaurus was found, only 8 complete skulls from 120 known species had been found
- Other fossils found (from three other specimens) include partial skulls, a partial hip, tail vertebrae, shoulder blade, some arm and hand bones
- Named in 2010 by Daniel Chure and others
- Type species is Abydosaurus mcintoshi
- Genus name means “Abydos lizard”
- Genus name refers to the town Abydos, the Greek name for the city now known as El Araba el Madfuna. It was where the head and neck of Osiris, the Egyptian god of life, death, and fertility, was buried, overlooking the Nile River, and the name alludes to the fact that the skull and neck was found in a quarry overlooking the Green River
- The species name is in honor of Jack McIntosh for his contributions to Dinosaur National Monument and the study of sauropods
- He’s a theoretical nuclear physicist professor, and after he retired he worked on sauropods
- McIntosh has written lots of papers and books on sauropods, and he helped show that Apatosaurus had the wrong head mounted on it in the 1970s (Camarasaurus skull)
- Skulls were on display at Brigham Young University’s Museum of Paleontology, where visitors could see students prepare the bones (while they were being prepped)
- All four skulls were about the same size, at about 1.6 ft (0.5 m) long
- At the time the dinosaur was named, the postcranial fossils were still being prepared (2010 paper said they’d be described at a later date)
- Had a similar skull to Giraffatitan, except for the teeth
- Abydosaurus also had a more narrow snout than Giraffatitan
- Had small nostrils
- Although now most people seem to accept that Abydosaurus was similar to Giraffatitan, in the 2010 paper the authors wrote that they “consider the decision to recognize the African species as a genus apart [from Brachiosaurus] to be arbitrary” so they mentioned Abydosaurus as being like Brachiosaurus
- They said they were open to the possibility of Giraffatitan being separate, but said “we do not believe that it is sufficiently justified at present because the identified differences have not been defended as separating genera, rather than species, populations, or individuals”
- Sauropod Vertebra Picture of the Week wrote at the time: “I am sort of nonplused by this. I’m certainly not saying that my 2009 paper is unassailable: as soon anyone comes along with evidence that Brachiosaurus and Giraffatitan should after all be considered congeneric, I’ll be first in line to hear them out. But I do feel that now 26 osteological differences have been described between the species, the null hypothesis has shifted, and the burden of proof is now on those who wish to synonymise the genera. “We choose to retain the original nomenclature” is not an argument, and doesn’t really advance understanding. So I’m afraid I think this was a regrettable misstep.” (They also were excited about the find and happy that John McIntosh got a sauropod named after him)
- Herbivorous
- Had heterodont teeth
- The upper and lower jaws had 14 teeth on each side
- Had narrow teeth, unlike earlier brachiosaurids with broader teeth
- Narrower teeth meant it probably had more teeth than Giraffatitan
- Replaced teeth quickly, even more quickly than Giraffatitan
- Grabbed and swallowed food
- From the 2010 paper: “The spartan design of sauropod skulls may be related to their remarkably small size—sauropod skulls account for only 1/200th of total body volume compared to 1/30th body volume in ornithopod dinosaurs.”
- Found that sauropods in the Cretaceous evolved to more rapidly replace teeth, not because of any major change in the diversity of plants around the world (though there were more conifers and angiosperms) but possibly because they changed their diets to eat “highly abrasive vegetation” or maybe they became more low browsing (“possibilities to be explored by future work”)
- Sauropods probably didn’t change much because the long necks and small skulls helped it to crop food quickly (maximized intake of food)
Fun Fact: Some dinosaurs ate grass, but humans eat much more grass than non-avian dinosaurs ever did.
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