Postosuchus kirkpatricki

Overview

Postosuchus was one of the top predators of the Late Triassic, approximately 228-202 million years ago! This massive archosaur was not a dinosaur, but it filled the same ecological role as large theropods would later. At up to 5 meters long and weighing as much as a grizzly bear, Postosuchus was the "T. rex before T. rex"!

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Taxonomy & Classification

• Phylum: Chordata
• Class: Reptilia
• Order: Rauisuchia
• Family: Poposauridae
• Diet: Carnivorous (apex predator)

Postosuchus was a rauisuchian—a group of crocodile-line archosaurs that were the dominant predators before dinosaurs took over.

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Physical Characteristics

Impressive Size

• Length: 4-5 meters (13-16 feet)
• Height: About 2 meters (6.5 feet) at the hip
• Weight: 250-300 kg (550-660 lbs)
• Comparison: Size of a large alligator, but more upright!

Fearsome Features

• Massive skull with powerful jaws
• Serrated teeth like steak knives
• Armored back with bony scutes (osteoderms)
• Strong legs positioned under the body
• Could possibly walk on two legs sometimes!

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Not a Dinosaur!

A Common Confusion

Postosuchus looked like a dinosaur but wasn't:

• It was a rauisuchian (crocodile-line archosaur)
• Dinosaurs are bird-line archosaurs
• They're related but different branches
• Think of it as a "cousin" to dinosaurs

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Walking Style

Upright Posture

Unlike modern crocodiles:

• Legs positioned under the body (not sprawling)
• Could walk efficiently for long distances
• May have been able to run bipedally
• More like a dinosaur in stance
• This is called "pillar-erect" posture

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Apex Predator

Terror of the Triassic

Postosuchus was at the top of the food chain:

• Hunted early dinosaurs (which were small then!)
• Preyed on dicynodonts and other herbivores
• Could take down prey larger than itself
• Had no natural predators as an adult
• Ruled before dinosaurs became dominant

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Discovery

Texas Fossils

• First discovered in 1980 in Texas
• Named in 1985 by Sankar Chatterjee
• Name means "Crocodile from Post" (Post, Texas)
• Multiple specimens found
• One of the best-known Triassic predators

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Habitat

Triassic North America

Postosuchus lived in:

• Semi-arid environments
• Areas that are now Texas, Arizona, New Mexico
• Landscapes with seasonal rivers and floodplains
• Forests of conifers and ferns

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Competition with Dinosaurs

The Rivals

During the Late Triassic:

• Postosuchus was the dominant predator
• Early dinosaurs like Coelophysis were small
• Rauisuchians outcompeted early dinosaurs
• Only after rauisuchians went extinct did dinosaurs take over!

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Extinction

End-Triassic Mass Extinction

Postosuchus disappeared due to:

• Mass extinction at the end of the Triassic
• 201 million years ago
• Volcanic eruptions and climate change
• This cleared the way for dinosaur dominance

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Cool Facts

• Postosuchus was the apex predator before dinosaurs took that role!
• It was NOT a dinosaur—it was more closely related to crocodiles
• Could grow up to 5 meters long—as long as a car!
• May have been able to run on two legs
• Had armored plates on its back for protection
• Named after Post, Texas where it was discovered
• Its extinction helped dinosaurs become the dominant predators
• Featured in the BBC documentary "Walking with Dinosaurs"

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Postosuchus shows us that before dinosaurs ruled the Earth, other incredible predators dominated—and it took a mass extinction to clear the way for the dinosaur age!