Episode 431: Was T. rex as smart as a baboon? Plus Evan Johnson-Ransom and Julius Csotonyi join us to discuss their new massive book titled Dinosaur World: Over 1,200 Amazing Dinosaurs, Famous Fossils, and the Latest Discoveries from the Prehistoric Era

News:

• A new study claims that theropods were as intelligent as primates (but not everyone agrees) source
• A single Allosaurus had 10 pathologies source
• An ornithomimosaur was injured via blunt force trauma to its foot source

Interview:

Julius and Evan join to talk about their new book. Evan Johnson-Ransom is a PhD student at the University of Chicago a studying the functional morphology and feeding behavior of dinosaurs. Julius Csotonyi is a talented paleoartist who has created life-sized dinosaur murals for many museums and also illustrated the new book Dinosaur World which Evan wrote.

Sponsors:

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Image by Alexoatss

The dinosaur of the day: Lurdusaurus

• Iguanodont that lived in the Early Cretaceous in what is now Niger (Elrhaz Formation)
• Looked similar to Iguanodon, but bigger
• So massive, probably quadrupedal
• Estimated to be about 23 to 30 ft (7 to 9 m) long and about 6.5 ft (2 m) tall when walking on all fours, but its stomach would only be a little over 2 ft (70 cm) above the ground (based on the length of the ribs)
• Weighed about 5.5 tonnes
• In 2016, Gregory Paul suggested Lurdusaurus was about 23 ft (7 m) long and weighed 2.5 tonnes
• In 2005, You Hailu and others said Lurdusaurus was classified in a group “distinguished by their massively-constructed body forms”
• Average adult hadrosaurids are 7 to 12 m long and 3000 kg
• Taquet and Russell, who officially named Lurdusaurus, described Lurdusaurus as ponderous (very heavy)
• Said that in a squat posture Lurdusaurus “must have somewhat resembled ankylosaurs”
• However, also said its small skull, circular chest, powerful forelimbs and claws, and other elements “probably even more strikingly recalled the form of giant ground sloths”
• Not a typical iguanotontid
• A large iguanodont, so large it walked on four legs
• Had a relatively small skull, long neck, massive forelimbs and thumb spikes, bulky body, relatively short tail and hindlimbs
• Estimated that the length of the skull of the holotype was about 2.9 ft (83.3 cm) long
• Had a beak (back of the skull was about 30 cm wide and front was 20 cm, so did not have a duck-like bill)
• Had between 12 and 14 neck vertebrae, and its neck estimated to be 5.3 ft (1.6 m) long
• Tail about 13 ft (4 m) long
• Had large, stout limbs
• Forelimbs are about 60% the size of the hindlimbs
• Had a short, powerful pelvis, somewhat similar to ceratopsians
• Femur has features like ceratopsians and sauropods
• Wrist bones were fused into a block
• Had a large thumb spike
• Taquet and Russell described the wrist and thumb claw as “reminiscent of a mace-and-chain”
• Probably used its thumb spike for defense
• Taquet and Russell found that the bones in the foot were reduced, so the metatarsals (bones leading up to the toes) “lost contact with each other, and that a fleshy pad must have supported most of the weight borne by the foot”
• In 2007 Tom Holtz suggested Lurdusaurus acted like a hippo and was semi-aquatic (only suggested though, no studies around this)
• Like a hippo, was stocky and usually moved slow but could move fast when needed
• Could be why there’s paleoart of Lurdusaurus swimming (with only the head above water)
• Type species is Lurdusaurus arenatus
• Fossils found in 1965 by Philippe Taquet
• Holotype is a nearly complete adult specimen, with a fragmentary skull
• Holotype only missing part of the skull, the sacrum, and a lot of the foot
• Found tooth punctures around the pubic bones, that were partly re-healed
• Taquet said it was large and in 1976 in a brief description said it should probably be its own genus
• In 1988 Souad Chabli described the specimen for her thesis and named it “Gravisaurus tenerensis” but her thesis was not published
• Formally named in 1999 by Taquet and Dale Russell
• Also referred a fragment of a dentary (lower jaw) and right coracoid (part of the shoulder) to Lurdusaurus
• Genus name means “heavy lizard”
• Species name means “sandy” and refers to the fossils being found in a desert
• Lived in a tropical forest
• Other dinosaurs that lived around the same time and place include iguanodonts Elrhazosaurus and Ouranosaurus, the sauropod Nigersaurus, titanosaurs, the spinosaurid Suchomimus, the carcharodontosaurid Eocarcharia, the abelisaurid Kryptops, and noasaurids
• Other animals that lived around the same time and place include crocodylomorphs and pterosaurs

Fun Fact:

Stegosaurus did not have a second brain at the base of its tail—but that was a real hypothesis proposed by O.C. Marsh.

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