Episode 96 is all about Irritator, a spinosaurid theropod whose name comes “from irritation, the feeling the authors felt (understated here) when discovering that the snout had been artificially elongated.”

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In this episode, we discuss:

• The dinosaur of the day: Irritator
• Irritaor is a spinosaurid theropod that lived in the Early Cretaceous in what is now Brazil
• Described in 1996 by Martill, Cruikskank, Frey, Small, and Clarke
• A new crested maniraptoran dinosaur from the Santana Formation (Lower Cretaceous) of Brazil, published in 1996
• More fully described in Irritator challengeri, a Spinosaurid (Dinosauria: Theropoda) from the Lower Cretaceous of Brazil, published in 2002
• Only one fossil found, of an 32 in (80 cm) long skull
• Nearly complete skull
• Not well preserved, there was plaster that obscured the fossil (added by fossil poachers who illegally sold the fossil to make the fossil look more complete)
• The buyers didn’t realize the amount of work required to restore the fossil when they bought it, and so they named it Irritator
• The authors wrote the name came “from irritation, the feeling the authors felt (understated here) when discovering that the snout had been artificially elongated”
• Type species is Irritator challengeri, and the species name is in honor of Professor Challenger, a character in Arthur Conan Doyle’s The Lost World (story about an expedition to the Amazon Basin where the characters find dinosaurs)
• Unknown where exactly the fossil was found (since it was sold illegally), but probably came from the Romualdo Member of the Santana Formation, based on the type of rock
• This area is about 110 million years old, and came from a time when Africa and South America were still connected in the north of Brazil
• Probably ate fish
• May have eaten other animals (whatever it could catch). There’s a pterosaur found with a tooth, probably from Irritator, in its neck, so may have eaten pterosaurs
• Had thin teeth, good for catching slippery prey
• Constantly replaced teeth
• Skull looks a lot like Suchomimus and Spinosaurus (crocodile-like head)
• Had nostrils at the back of its skull (crocodile-like head)
• Thought to have a Sagittal crest, a bony ridge on the top of the skull that’s attached to the jaw muscles
• Sagittal crest means it probably had strong neck muscles, so could close its jaws quickly even in water, but that doesn’t mean it specialized in eating fish
• Often considered to be synonymous with Angaturama, which lived at the same time and place. Also the fossils found on Angaturama seem to complete the Irritator fossil, so they could be the same specimen
• Angaturama was described in 1996, after Irritator, based on a fossil found in the Santana formation. Later 60% of the skeleton was found, so a replica was made and put on display at the Rio de Janiero National Museum. Several paleontologists think Irritator and Angaturama are different, based on Angaturama having a higher, more flattened head
• Diane Scott fully cleaned the skull, and a new paper was published in 2002 to further describe Irritator
• Had a narrow skull with an elongated snout (back of the skull was deeper than originally thought)
• Teeth similar to Spinosaurus aegyptiacus, but hard to compare other parts because of lack of fossils
• Also found it didn’t have a crest
• In 2004 parts of a spinal column of a spinosaurid were found in the Santana Formation, and they are thought to belong to Irritator
• It was estimated to be about 26 ft (8 m) long, though Gregory Paul said in 2010 it may only have been 7.5 m long
• May have had a sail, but that’s a guess since no fossil has been found
• Fun fact: Although it’s illegal to export fossils from China, the Psittacosaurus, “SMF R 4970”, was taken out of China and sold on the black market a few times before being bought by the Senckenberg museum in Germany. So if you live nearby you should go soon, in case it gets repatriated back to China. The Senckenberg museum may not have known that the fossil was smuggled out when they bought it since the law used to be less well known. But according to an article by Liston and You, things were clarified a bit in 2013. If you’re wondering if a specimen was legally exported from China “the most effective way to check is to look for the unique Ministry of Land and Resources registration number, with which your material should have arrived. If your material has this number, then it has left the People’s Republic of China legally. If your Chinese fossil material does not have this number, then it is appropriate to be concerned as to just how it came to leave that country.”

This episode was brought to you by:

The Royal Tyrrell Museum. The Royal Tyrrell Museum is located in southern Alberta, Canada. One of the top paleontological research institutes in the world, the entire museum is dedicated to the science of paleontology. It’s definitely a must see for every dinosaur enthusiast. More information can be found at tyrrellmuseum.com.