Episode 70 is all about Mapusaurus, one of the largest carnivorous dinosaurs found so far.

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In this episode, we discuss:

• The dinosaur of the day: Mapusaurus
• Name means “earth lizard”
• Type species is Mapusaurus roseae, named after the rose-colored rocks where Mapusaurus was found and for Rose Letwin, who sponsored the fossil excavation
• Lived in the Cretaceous in what is now Argentina
• First discovered in 1995
• Excavated between 1997 to 2001 as part of the Argentinian-Canadian Dinosaur Project
• Phil Currie and Rodolfo Coria described Mapusaurus in 2006
• Found in the Huincul Formation, which was an arid environment
• Bone bed with Mapusaurus had at least seven individuals (different ages); may be because of a predator trap or because they lived together
• Bone bed may have been a result of the bones being carried downstream in a flood (no other dinosaurs found in the bone bed)
• They may have hunted in packs, but it’s unclear for certain
• Other sites have been found with many carnivorous dinosaurs in Alberta, Mongolia, and the U.S., which suggests in the Cretaceous there may have been pack behavior
• Smallest individual found in the bone bed was 18 ft (5.5 m) long
• Some as large as 33 ft (10.2 m) long and weighing 3 tons (some sources say up to 8 tons); similar in size to Giganotosaurus, a close relative
• Coria and Currie in 2006 said they found larger femur bones similar in size to a Giganotosaurus that was 40 ft (12.2 m) long and in Drew Eddy and Julia Clarke in 2011 found a pubic shaft that was even larger than the Giganotosaurus so they said Mapusaurus may have been as long as 41 ft (12.6 m), or even larger
• Mapusaurus may be the biggest carnivorous dinosaur found so far
• 6 ft (1.84m) long skull
• Similar to Giganotosaurus but the skull was a little different (thicker, wider, flatter)
• Skull is lower and lighter than Giganotosaurus
• Lived alongside Argentinosaurus and Cathartesaura, as well as the abelisauroids Skorpiovenator and Ilokelesia
• Unclear what Mapusaurus would have hunted, if it hunted (instead of scavenged)
• Adult Argentinosaurus could weigh up to 100 tons (125 ft or 40 m long); too large to hunt alone
• May have gone after a juvenile Argentinosaurus (as a group)
• Teeth are similar to Giganotosaurus (flat, curved with a serrated edge, which are good for slicing, compared to T-rex which had conical teeth, good for crunching bone)
• May have not been able to bite through Argentinosaurus bone (as a pack, multiple bites so Argentinosaurus would lose blood or get infected), then they could eat it when it’s weaker
• From 2013: Palaeopathological Survey of a Population of Mapusaurus (Theropoda: Carcharodontosauridae) from the Late Cretaceous Huincul Formation, Argentina on PLOS One: Scientists studied all the Mapusaurus found in the bonebed and looked for diseases and trauma (paleoepidemiology). They found two broken and re-healed ribs (led an active lifestyle, but no skeletal abnormalities (so far, studies of theropods show low numbers of abnormalities)
• Mapusaurus is a carcharodontosaurid
• Carcharodontosaurids (name means “shark-toothed lizards) were carnivorous theropods
• Ernst Stromer named the family in 1931
• Family includes Giganotosaurus, Mapusaurus, Carcharodontosaurus, and Tyrannotitan (all about same size or larger than T-rex)
• Carcharodontosaurids and spinosaurids were the largest predators in Gondwana in the early and middle Cretaceous
• Mapusaurus is part of the subfamily Giganotosaurinae (carcharodontosaurids more closely related to Giganotosaurus and Mapusaurus than Carcharodontosaurus)
• Fun fact: According to National Geographic cassowaries and Harpy eagles have the longest claws of any living bird at about 4 to 5 in (~10-13 cm) long. But those claws are actually two parts, a bone and then a sharp keratin covering over the top. Claw sheaths rarely fossilize since they are made from keratin so we are usually just left with the bone underneath the claw sheath. So when you go to a museum and see a mounted skeleton, unless they add an extrapolated sheath to the fossil you’re seeing a claw that’s significantly shorter, and likely more dull, than the full claw would have been.