Iguanodon bernissartensis ig-WAN-oh-don

"Iguana tooth"

Iguanodon silhouette
You 1.8 m (5.9 ft) tall
Iguanodon 10 m (33 ft) long
6 people holding hands
silhouette · Matthew Dempsey (CC-BY) via PhyloPic
Length
10 m (33 ft) — About 10 m long, ~3 tonnes — large bipedal herbivore with thumb spikes.
Period
Early Cretaceous (126–122 Mya)
Place
Europe · Belgium · England · Germany
Food
Herbivore — Cycads, ferns, conifer needles — chewed by a sophisticated jaw that worked like grinding teeth.
Clade
Iguanodontia Dinosauria Ornithischia Cerapoda Ornithopoda

Iguanodon was the second dinosaur ever named, in 1825. The first scientists thought it was a giant iguana — they put its thumb spike on its nose, mistaking it for a horn. Decades later, when 38 complete skeletons were dug out of a coal mine in Belgium, paleontologists finally understood: the spikes were thumbs, the body was that of a giant bipedal plant-eater.

What we know

  • Second dinosaur ever named (after Megalosaurus), in 1825.
  • Iconic thumb spike — possibly defensive, possibly for cracking seeds.
  • 38 complete skeletons found in a Belgian coal mine in 1878 — the famous Bernissart specimens.
  • Sophisticated chewing teeth that worked like a grinding mill.

What we guess

  • Whether the thumb spike was a weapon, a tool for breaking seeds, or both.
  • Whether it walked on two legs or four — modern view says it could do both depending on need.
  • How big the herds were — Bernissart suggests groups, but might be an accumulation.