Irritator challengeri is a genus of spinosaurid dinosaur that lived in what is now Brazil during the Albian stage of the Early Cretaceous Period. It is known from a nearly complete skull found in the Romualdo Formation of the Araripe Basin. Fossil dealers had acquired this skull and illegally sold it to the State Museum of Natural History Stuttgart. The species name is an homage to the fictional character Professor Challenger from Arthur Conan Doyle’s novels.
About Irritator in brief
Irritator challengeri is a genus of spinosaurid dinosaur that lived in what is now Brazil during the Albian stage of the Early Cretaceous Period, about 110 million years ago. It is known from a nearly complete skull found in the Romualdo Formation of the Araripe Basin. Fossil dealers had acquired this skull and illegally sold it to the State Museum of Natural History Stuttgart. The genus name comes from the word “irritation”, reflecting the feelings of paleontologists who found the skull had been heavily damaged and altered by the collectors. The species name is an homage to the fictional character Professor Challenger from Arthur Conan Doyle’s novels. Irritator weighed around 1 tonne, making it one of the smallestspinosaurids known. It may have had semiaquatic habits, and inhabited the tropical environment of a coastal lagoon surrounded by dry regions. It coexisted with other carnivorous theropods as well as turtles, crocodyliforms, and a large number of pterosaur and fish species. One possible skeleton indicates it had enlarged first-finger claws and a sail running down its back. A generalist diet—like that of today’s crocodilians—has been suggested; Irritators might have preyed mainly on fish and any other small prey animals it could catch. It had a long, shallow and slender snout was lined with straight and unserrated conical teeth. Lengthwise atop the head ran a thin sagittal crest, to which powerful neck muscles were likely anchored.
The nostrils were positioned far back from the tip of the snout. A rigid secondary palate on the roof of the mouth would have strengthened the jaw when feeding. The Angaturama snout tip expanded to the sides in a rosette-like shape, bearing long teeth and an unusually tall crest. It was also previously proposed that IrritATOR and AngaturAMA’s skull parts belonged to the same specimen. Although this has been cast into doubt, more overlapping fossil material is needed to confirm whether they are the same animal or not. Other spinosaurusid skeletal material, some of which could belong to Irritater or Angaturamas, was retrieved from the RomUALdo Formation, allowing for a replica skeleton to be made and mounted for display at the National Museum of Rio de Janeiro in 2009. The holotype skull was thoroughly prepared before being redescribed in 2002, confirming this classification. The right side of the fossil was well-preserved while the left side was partly crushed, while the hindmost end lacked the lower jaw end, owing to breakage during its front end being cracked. Some of the skull’s hindmost surface had eroded, and the lower end of its lower jaw lacked the front end, due to its frontend being cracked during its break-age. At the time it was assumed to be the skull of a giant basal pterosaursaur, or flying reptile.