The Big Dinosaur Podcast

Episode 323 is all about Mantellisaurus, an iguanodontian dinosaur known from a remarkably complete holotype mounted next to Dippy’s former home in the Natural History Museum, London.

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In this episode, we discuss:

News:

• The most likely way Spinosaurus hunted (spoiler alert: it’s not swimming like a shark) source
• A new megalosauroid from the relatively unknown Middle Jurassic Xintiangou formation in China source
• Three baby tyrannosaur finds fill in gaps about their early lives & nesting habits source
• Work has started on the Mary Anning statue, the goal is to unveil it on May 21, 2022 (her birthday) source
• The videogame Stardew Valley features dinosaur eggs that can be discovered and hatched into living dinosaurs source
• Colin Trevorrow said that there won’t be “people riding dinosaurs with shotguns” in Jurassic World Dominion source

The dinosaur of the day: Mantellisaurus

• Iguanodontian that lived in the Early Cretaceous in what is now western Europe (found in Belgium, England, Spain, and Germany)
• Looks like Iguanodon, originally thought to be Iguanodon (if you saw it might think it was Iguanodon)
• More lightly built than Iguanodon, and more closely related to Ouranosaurus
• Probably more derived than Iguanodon
• Probably semi-quadrupedal, and walked on all fours when standing still or moving slowly
• Wrists fused together
• Hands look like hooves, so could probably walk on them
• Forelimbs were shorter proportionally to Iguanodon bernissartensis (about half the length of its hindlimbs)
• The arm bone, humerus, had a ridge known as the deltopectoral crest, which probably means it had powerful deltoid and pectoral muscles
• Estimated to be 23 ft (7 m) long
• Weighed about 1650 lb (750 kg)
• Had a low skull
• Had an hourglass shaped head, when seen from above
• Herbivorous
• Had teeth up to 1.5 in (40 mm) tall
• Had dental batteries
• Had a large beak
• Had tall neural spines with ossified tendons, may have had a ridge along its back
• Had large thumb claws/spikes, possibly used for defense (but arms were pretty short, so maybe used to fight with other Mantellisaurus, or to dig out roots or tear bark off trees or open fruit)
• Trackways found in the same area as the holotype, and may show they travelled in groups (juveniles and adults)
• Type and only species is Mantellisaurus atherfieldensis
• Used to be known as Iguanodon atherfieldensis
• Genus name means “Mantell’s lizard”
• Genus name in honor of Gideon Mantell, who discovered Iguanodon
• Gideon Mantell had a sad story. He became obsessed with dinosaurs and stopped his medical practice. He wrote books that didn’t really sell, and though he sold fossils to the British Museum, he couldn’t make a living as a paleontologist, so his wife and kids eventually left him. He died very bitter, with a spinal injury, on November 10, 1852
• Species name is in honor of Atherfield, the village on the Isle of Wight where the holotype was found
• Holotype, NHMUK R5764, was found in 1914 by amateur paleontologist Reginald Walter Hooley in southern England, and reported in 1917
• Hooley posthumously named it Iguanodon atherfieldensis in 1925
• Named by Gregory Paul in 2007
• Lots of complete and nearly complete skeletons found
• Iguanodon has been described as a wastebasket taxon (Darren Naish and David Martill said in 2008 it was “taxonomic dumping grounds”); also been called a taxonomic grab bag
• Found in many parts of Europe, and has gone by many names
• The Maidstone specimen (talked about in episode 87, Iguanodon)
• Found in a quarry in Maidstone, Kent in 1834. Part of it was blown apart by gunpowder and scattered, but a lot of it was on a large slab of “Kentish Rag” sandstone. William Harding Bensted owned the quarry and excavated the fossils, then wrote to Gideon Mantell. Mantell said it was an Iguanodon, based on teeth, and he offered to pay £10. Bensted asked for £25. Took a couple months, then Mantell and his friends got the money and bought what they called the “Mantell-piece”, which eventually became the dinosaur on Maidstone’s coat of arms
• Mantell based his Iguanodon restoration on the Maidstone specimen, but he made some mistakes (thought there was a horn on the snout)
• More Iguanodon specimens found later made it clear that horn belonged on the thumb
• The Maidstone specimen was considered to be Iguanodon anglicus (now at the Natural History Museum in London). Turns out, it came from a type locality much higher than where the original Iguanodon teeth came from, so it probably can’t be. In 1888 Richard Lydekker said the specimen was the lectotype of Iguanodon mantelli but Iguanodon mantelli was named two years before the Maidstone specimen was found (so that wasn’t accepted)
• Maidstone specimen now classified as possibly Mantellisaurus atherfieldensis (cf, which means very uncertain)
• Dollodon bampingi, found in Belgium, is considered to be a junior synonym of Mantellisaurus atherfieldensis
• Originally, this specimen was thought to be Iguanodon mantelli (named in 1881 by George Albert Boulenger), then thought to be Iguanodon atherfieldensis (1986, David Bruce Norman), then named new genus Dollodon bampingi by Gregory Paul in 2008 based on being more quadrupedal compared to Mantellisaurus, which had shorter forelimbs proportionally and a larger pelvis and therefore more likely to be bipedal. Then in 2010 Kenneth Carpenter and Yusuke Ishida synonymized Dollodon with Iguanodon seeli, based on a specimen from Wessex Formation, England. Then in 2012, Andrew McDonald and David Norman said Dollodon was Mantellisaurus
• Specimens also found in Sauerland, Germany (disarticulated) and in Spain (articulated hindlimb from Las Hoays, three specimens from the Arcillas de Morella Formation, and a specimen from the Rubielos de Mora locality)
• Fossils found in Sauerland were thought to be Vectisaurus valdensis, then in 1990 David Norman found them to be juvenile Iguanodon atherfieldensis
• Some of the places it was found, there was probably a flash flood or mudslides, such as in Sauerland
• Fossils found in Haute-Marne, France were originally called Heterosaurus neocomiensis, named by Jacques Cornuel in 1850 and thought to be different because it’s teeth were different from Iguanodon, Hylaeosaurus, and Megalosaurus (full name means “different lizard from the Neocomian”); specimen was medium sized. In 1968 it was redescribed and stored with Iguanodon material, then in 1992 Valérie Martin and Eric Buffetaut found it to closely resemble Iguanodon atherfieldensis
• Mantellisaurus (holotype) is on display in a glass case in Hintze Hall, at the Natural History Museum in London
• Known by the nickname Mantelli
• Had been in the hall since 2017, and before that was hung from the ceiling in the Dinosaurs gallery
• Originally the Natural History Museum in London had Mantellisaurus standing like a kangaroo with its tail dragging, then shown as semi-quadrupedal, with its tail lifted, to help show movement
• The skeleton was removed temporarily in 2019 to scan all the bones to study them and make the data available to scientists around the world
• Did all the scans in three days. They waited for the museum to close one evening then took the bones from the mount
• The team used laser and handheld scanners to build high-resolution digital models of the fossils
• Some of the bones were left in the mount because they’re attached to it (pelvic area), so they used a handheld scanner
• The skeleton is nearly 86% real bone, and casts make up the rest (have the left arm, but not the right arm, for example)
• Real skull is not on display, and instead stored in the basement
• Susannah Maidment, who was in charge of the scanning, said they found some differences between past descriptions of Mantellisaurus and what they saw with the scans, so there will be a redescription of the holotype

Fun Fact: In Chinese, Velociraptor is sometimes translated as Xunmenglong (the new compsognathid we mentioned last week). The Jurassic Park series uses that translation as well, which is sure to further confuse fans about what Velociraptor really looked like.