Episode 413: A sparkly dinosaur that mummified like an Egyptian. Plus T. rex had smaller eyes for a stronger bite, a study of Sue’s jaw holes, dinosaur fossils lost in a shipwreck, and much more

News:

• An Edmontosaurus from the Hell Creek formation nicknamed Dakota likely desiccated for weeks before being buried and fossilizing source
• The new dinosaur Mbiresaurus helps show that the earliest dinosaurs lived in the far south of Pangaea in temperate climates source
• New dinosaur Nevadadromeus schmitti has officially been published source
• Having narrower eye sockets may have helped tyrannosaurs and other large theropods to have a more powerful bite source
• How SUE the T. rex got holes in its jaws remains a mystery source
• In Australia, Muttaburrasaurus is officially Queensland’s State Fossil source

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The dinosaur of the day: Amphicoelias

• Diplodocid sauropod that lived in the Late Jurassic in what is now Colorado, U.S.
• Probably looked like other sauropods, specifically diplodocids, with a long neck, long whip-like tail, walked on four legs (and was very large)
• Estimated to be about 59 ft (18 m) long and weigh 17 short tons
• For a long time, thought to be one of the largest known dinosaurs
• Amphicoelias altus (type species) looks very similar to Diplodocus
• Had long, thin hindlimbs
• Forelimbs were proportionally longer than other dinosaurs it was closely related to
• Had a long, slender femur
• Three species named: altus, latus, fragillimus
• Only one valid species now, the type species
• Type species is Amphicoelias altus
• Fossils found by Oramel William Lucas, near Cañon City in Colorado in 1877
• Described by Edward Drinker Cope shortly after, in 1877
• Cope received the fossils in October 1877 and named Amphicoelias in December 1877
• Bone Wars dinosaur, which is probably why Cope described it so quickly (episode 250)
• Genus name means “both sides hollow”
• Cope wrote in 1877 about the fossils Lucas sent him:
• “He also procured remains of two additional forms of gigantic size, fit rivals of the Camarasaurus, which I referred to the new genus Amphicoelias. A species of tortoise was associated with these saurians, and appears to have been abundant”
• Said it was “allied to Camarasaurus”
• Also wrote that Camarasaurus and Amphicoelias “attained to the most gigantic proportions”
• Cope thought the fossils were from the Cretaceous, the same time as the Laelaps fossils (Cope also named)
• Cope said there were differences in the vertebrae, so it was distinct from Camarasaurus
• Cope described lots of back vertebrae, a pubis, and femur
• Later, Henry Osborn and Charles Mook described it as only having two vertebrae, as well as a pubis, femora, a tooth, ulna (part of the forelimb) and parts of the shoulder (these fossils found near the holotype and they were different from Camarasaurus–they were found alongside a Camarasaurus). But Emanuel Tschopp and others questioned this assignment of fossils to Amphicoelias when analyzing Diplodocidae in 2015. Though they did accept the ulna as being part of Amphicoelias
• Amphicoelias latus
• Cope also named Amphicoelias latus, based on a femur and tail vertebrae. Osborn and Mook in 1921 later said that belonged to Camarasaurus, and referred it Camarasaurus supremus
• Osborn and Mook found the fossils were more similar to Camarasaurus than Amphicoelias
• Later, in 1998, McIntosh also suggested that Amphicoelias latus was a synonym of Amphicoelias altus
• Amphicoelias latus is now considered to be a synonym of Camarasaurus supremus.
• Amphicoelias fragillimus
• This is the one that has been talked about the most
• Species name fragillimus refers to the fragility of the fossil, which had a lot of thin parts
• Amphicoelias fragillimus fossil found near Camarasaurus supremus fossils, by Oramel Lucas (Lucas shipped to Cope in spring or early summer of 1878 and Cope published about it that August)
• Cope named Amphicoelias fragillimus in 1878 based on a large back vertebra, that later was lost
• Cope visited Lucas and the quarries in the summer of 1879 and wrote notes about more Amphicoelias fragillimus fossils (neural spine and femur) but those have been lost
• In 1994 there was an attempt to find the quarry where the Amphicoelias bones were originally found, but the technique didn’t work (used radar but the density of the fossils were the same as the matrix the bones were in, so couldn’t find the fossils). Also the mudstone “is nearly stripped down to the underlying sandstone” according to Carpenter, and based on local topography this probably happened before Lucas found the Amphicoelias fossil, which means most of the Amphicoelias skeleton was probably destroyed a long time before he found the neural spine
• Back to the vertebra, which Cope based the name on
• Cope in 1878 wrote about Amphicoelias fragillimus that the “dimensions of its vertebra much exceed those of any known land animal”
• Based on an illustration from 1878, the vertebra was about 8.9 ft (2.7 m) tall. Though the illustration may have had a typographical error with the scale bar
• Earlier estimates for Amphicoelias fragillimus were 130 to 200 ft (40 to 60 m) long and weighed up to 150 tons
• Some skepticism around the size of Amphicoelias
• In 2015, Cary Woodruff and John Foster found that the giant size of Amphicoelias fragillimus was “most likely an extreme over-estimation”
• Based on previous estimates, would make Amphicoelias fragillimus the largest vertebrate every (the largest blue whale is about 98 ft or nearly 30 m long)
• Woodruff and Foster said that based on bone strength, muscle forces, and gravity, animals that lived on land could only get as heavy as about 100 tons (about 90,700 kg)
• Also said that larger animals need more food, and in the ecosystem where Amphicoelias lived, there were lots of large sauropods that would also have needed to eat lots of vegetation
• Woodruff and Foster said they thought there was a typographical error when it came to the size of Amphicoelias material
• Said Cope had lots of typographical errors in his work, and sometimes he even said the species was “fragillimus” and sometimes “fragillisimus”
• Carpenter wrote in 2006, “There is every reason to suspect that Amphicoelias fragillimus was indeed one of the largest, if not the largest dinosaur to ever walk the earth”
• Also should mention, it’s accepted that Cope did describe a large vertebra and it belonged to a giant dinosaur
• Amphicoelias fragillimus fragmentary vertebra was 1.5 m high (4.9 ft)
• Carpenter said there was every reason to accept Cope at his word (he never made any corrections in later publications, Marsh never called him out, and Osborn and Mook accepted the measurements in 1921, as did McIntosh in 1998)
• Strange though, Cope didn’t mention Amphicoelias fragillimus in any more scientific papers after describing it
• Cope said the specimen was delicate and required great care, so it’s possible the fossil crumbled and then was discarded
• Carpenter estimated Amphicoelias fragillimus weighed around 122,400 kg (about 135 tons), based on scaled up proportions of Diplodocus
• Carpenter in 2006 also studied the paleobiology of sauropods and suggested their large sizes made them more efficient in digesting food, similar to elephants and rhinoceros. This is because they had longer digestive systems and could digest food over a long period of time, which helped them survive on lower quality plants
• Carpenter also suggested that other benefits of being large, like being safer from predators, not having to use as much energy, and living longer, were secondary benefits compared to the digestion reason
• Amphicoelias lived in a savanna-like environment
• Probably ate ferns
• Amphicoelias fragillimus vertebra was lost sometime when Cope sold his fossils to the AMNH
• However, it was still assigned an AMNH catalog number even though it was never seen at the AMNH because Cope didn’t number anything, so they numbered everything based on notes to be assigned when it turned up
• Catalogued as AMNH 5777: “Amphicoelias fragillimus, Holotype.”
• In 1921 Osborn and Mook provisionally synonymized Amphicoelias fragillimus with Amphicoelias altus (saying Amphicoelias fragillimus was a large individual of Amphicoelias altus)
• Osborn and Mook wrote “The type of this species has not been found in the Cope Collection, and its characters cannot be clearly determined.”
• In 2018 Kenneth Carpenter renamed Amphicoelias fragillimus as Maraapunisaurus
• Covered Maraapunisaurus and Amphicoelias in episode 210
• When Carpenter named Maraapunisaurus, he made some new estimates on the fossil, mainly that the vertebra was about 2.4 m tall instead of 2.7 m and Maraapunisaurus (formerly Amphicoelias fragillimus) was about 99 to 105 ft (30.3 to 32 m) long
• Species debates
• In 2010 Henry Galiano and Raimund Albersdorfer had a paper that referred fossils found in the Big Horn Basin in the Morrison Formation in Wyoming (fossils from a private collection) to a new species, Amphicoelias brontodiplodocus
• They hypothesized that most diplodocids found in the Morrison Formation represented different growth stages or sexual dimorphism and they were all Amphicoelias
• But this paper was never formally published and the lead author even said it was just a drafted manuscript
• John Foster in 2007 suggested that the features of Amphicoelias altus that made it unique might just be due to individual variation and that Amphicoelias may be a senior synonym of Diplodocus
• In 2015 Woodruff and Foster made the same suggestion, that there is only one species of Amphicoelias and it could be referred to Diplodocus
• Woodruff and Foster suggested that the differences between all the species was due to ontogeny (growth) and that the fossils for Amphicoelias altus was an immature specimen and the fossils for Amphicoelias fragillimus were from a more mature specimen
• Because of this, they suggested that Amphicoelias fragillimus should be synonymized to Amphicoelias altus
• Also said there weren’t legitimate unique features for Amphicoelias altus and supported referring all Amphicoelias material to Diplodocus altus. Because Amphicoelias was named first, Diplodocus would become Amphicoelias, but they said Amphicoelias should be a nomen oblitum, (a name that hasn’t been used scientifically for more than 50 years after originally being named, and it’s been replaced by a more recent name that is commonly used) and the name should stay Diplodocus
• In 2021, Philip Mannion, Emanual Tschopp, and John Whitlock redescribed Amphicoelias altus
• Found Amphicoelias altus to be valid
• AMNH got the Amphicoelias altus fossils in 1902, and according to the museum, they’re the earliest recovered fossils currently in their collection
• The team in 2021 analyzed the fossils and found three features, that have to do with the shape of the vertebrae and femur, that made Amphicoelias a valid taxon
• Type and only species is Amphicoelias altus
• Right femur is currently in three pieces but mostly complete in length
• Team could not get permission to do histology but based on the size of the femur, think the individual was an adult (unclear if it was a young adult and still growing or an older adult, but there were no features “associated with advanced age”)
• Found that only the holotype represented Amphicoelias altus (no referred specimens)
• Also found there was probably even more diversity in sauropods in the Morrison Formation than previously thought

Fun Fact:

There are at least 10 ways fossils can be destroyed, including one case of a WWI shipwreck that lost 22 crates of dinosaur bones.

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