Apatosaurus vs Irritator

A detailed side-by-side comparison of Apatosaurus and Irritator, covering size, diet, classification, geologic period, and discovery history.

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Side-by-Side Comparison

Property Apatosaurus Irritator
Scientific Name Apatosaurus ajax Irritator challengeri
Classification Sauropoda Spinosauridae
Period Jurassic Late Cretaceous Early
Diet Herbivore Piscivore
Length 22.0 m 8.0 m
Height 4.5 m 2.5 m
Weight 22.7 t 1.0 t
Discovery Year 1877 1996
Discovery Location Morrison Formation, Colorado, USA Santana Formation, Brazil
Named By Othniel Charles Marsh David Martill et al.
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Size Comparison

Apatosaurus 22.0 m

about as long as 4 cars end-to-end

Irritator 8.0 m

roughly the length of a large SUV

Weight Comparison

Apatosaurus 22.7 t

about the weight of 3.8 elephants

Irritator 1.0 t

comparable to 1.0 small cars

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Timeline Comparison

Apatosaurus
161.5 Mya Jurassic Late (Mesozoic) 145.0 Mya
Irritator
145.0 Mya Cretaceous Early (Mesozoic) 100.5 Mya
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Diet Comparison

Apatosaurus

Herbivore

Apatosaurus was a plant-eater, feeding on vegetation like ferns, conifers, and cycads.

Irritator

Piscivore

Irritator was a fish-eater, specialized in catching aquatic prey.

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Classification Comparison

Apatosaurus

Clade: Sauropodomorpha

Group: Sauropoda

(Lizard feet)

Irritator

Clade: Theropoda

Group: Spinosauridae

(Spine lizards)

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Did You Know?

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Apatosaurus was about 2.8x longer than Irritator.

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Apatosaurus weighed roughly 23x more than Irritator.

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Apatosaurus was a herbivore while Irritator was a piscivore.

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Apatosaurus lived during the Jurassic Late while Irritator lived during the Cretaceous Early, separated by roughly 0 million years.

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Apatosaurus was discovered 119 years earlier, in 1877.

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Apatosaurus belonged to Sauropoda while Irritator belonged to Spinosauridae.

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