Irritator challengeri

Overview

Irritator is a dinosaur with one of the most unusual names in paleontology—and the story behind it is just as unusual! This medium-sized spinosaurid lived approximately 110-100 million years ago during the Early Cretaceous in what is now Brazil. With its crocodile-like snout and semi-aquatic lifestyle, Irritator was a skilled fish-hunter of the ancient South American coastline.

---

Taxonomy & Classification

• Clade: Theropoda
• Family: Spinosauridae
• Diet: Carnivorous (primarily fish)
• Locomotion: Bipedal

Irritator was closely related to Spinosaurus and Baryonyx.

---

Physical Characteristics

Size & Build

• Length: 7-8 meters (23-26 feet)
• Height: About 2 meters (6.5 feet) at the hip
• Weight: About 1,000 kg (1 ton)
• Skull Length: About 80 cm (31 inches)

The Classic Spinosaurid Look

• Long, narrow snout like a crocodile
• Conical teeth for gripping slippery prey
• Sagittal crest on top of the skull
• Slender, lightweight build
• Designed for speed and agility

---

That Irritating Name!

Why "Irritator"?

This dinosaur has one of the funniest naming stories:

• The fossil was found by local collectors in Brazil
• Before scientists got it, the collectors altered the skull with plaster!
• They tried to make it look more impressive to sell it
• Paleontologists had to carefully remove all the fake parts
• This was extremely irritating and frustrating work
• So they named it Irritator—to express their annoyance!

The Species Name

• "challengeri" honors Professor Challenger
• Challenger is a fictional character from Arthur Conan Doyle's novel The Lost World
• The novel is about explorers finding living dinosaurs in South America
• Very fitting for a South American dinosaur!

---

Fishing in Brazil

Diet & Hunting

Irritator was a fish-eating specialist:

• Crocodile-like jaws perfect for snapping at fish
• Interlocking conical teeth held slippery prey
• Probably hunted like a heron or bear
• Stood in shallow water and struck at fish
• Also ate pterosaurs—one was found as stomach contents!

The Pterosaur Meal

We know one of Irritator's meals:

• Fossil found with pterosaur bones in the stomach area!
• The pterosaur was Anhanguera
• Shows Irritator wasn't just a fish-eater
• Would catch flying reptiles near the water!

---

Living in Cretaceous Brazil

The Santana Formation

Irritator lived in a unique environment:

• Now part of northeastern Brazil
• Was once a coastal lagoon environment
• Warm, shallow waters teeming with fish
• Many pterosaurs flew overhead
• Part of an inland sea in Gondwana

Ecosystem Neighbors

Irritator shared its world with:

• Anhanguera and other pterosaurs
• Calamopleurus and other large fish
• Turtles and crocodilians
• Other dinosaurs in nearby areas

---

Irritator vs. Angaturama

The Same Dinosaur?

There's a mystery about Irritator:

• Angaturama limai was named from a snout tip
• Found in the same formation as Irritator
• Many scientists think they're the same species!
• The snout might even fit the back of Irritator's skull
• If so, we call it Irritator (the older name takes priority)

---

Smaller but Deadly

A Medium-Sized Predator

Compared to other spinosaurids:

• Smaller than Spinosaurus or Suchomimus
• About the same size as Baryonyx
• But still a powerful predator in its environment
• Its smaller size may have made it more agile

Spinosaurid	Length	Location
Spinosaurus	14-18m	Africa
Suchomimus	9-12m	Africa
Baryonyx	7.5-10m	Europe
Irritator	7-8m	South America

---

Discovery & Science

Fossil History

• Skull found in the 1990s in Brazil
• Purchased from fossil dealers
• Scientists realized it had been tampered with
• Named in 1996 by Martill and colleagues
• Additional material described since then
• Helps understand spinosaurid evolution in South America

---

Cool Facts

• Irritator is named after the frustration of dealing with a faked fossil!
• It ate at least one pterosaur—we have the proof!
• The species name honors a fictional professor from a dinosaur novel
• Irritator and Angaturama might be the same animal with two names
• It had a bony crest running along the top of its skull
• One of the few spinosaurids known from South America
• The original fossil was modified with plaster to look better—very naughty!

---

Irritator is proof that sometimes science can be frustrating—but even an annoying fossil can teach us amazing things about prehistoric fish-eating dinosaurs!