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Invictarx, Late CretaceousMenefee Formation, New Mexico · named 2018
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Invictarx

"unconquerable fortress"

Lived
84 to 72 million years ago, Late Cretaceous
Diet
Herbivore
Group
Ankylosaurs, Nodosauridae
Found in
United States
Named by
McDonald and Wolfe 2018

Where its fossils were found

The evidence

Today

1 find

80 million years ago

Map: C. R. Scotese, PALEOMAP

Habitat

It lived in the warm, swampy landscape of the Menefee Formation in New Mexico. Its neighbors included Dynamoterror, Menefeeceratops and Ornatops.

Field notes

About Invictarx

What it was like

Invictarx was a nodosaur, an armored plant eater without a tail club. It is known from pieces of its armor, which show a pattern of plates unlike those of its relatives.

Its world

It lived in the Late Cretaceous in what is now New Mexico. Its bones come from the Menefee Formation, a warm, swampy land shared with the tyrannosaur Dynamoterror and the horned Menefeeceratops.

How it was found

McDonald and Wolfe named it in 2018 from armor and rib fragments, and assigned two more finds to it.

Field gallery

More views of Invictarx

Scenes reconstructed from the available fossil evidence.

Invictarx in its habitat, photo 1

1 of 2

Lived alongside

Found in the same rock formations

A rock formation can hold fossils laid down millions of years apart, so not every animal here met Invictarx.

The evidence

The science behind Invictarx

Which parts of the picture come from its own bones, and which come from its relatives.

From its own fossils

  • The type specimen is mostly armor plates and pieces of ribs. Two more finds assigned to it add damaged vertebrae, front leg bones and more armor.
  • The armor plates are fairly smooth, with scattered pits and a few grooves. Some carry a low, rounded ridge split by a groove along the top.
  • Some plates probably joined into a shield of many-sided pieces over the hips.

Borrowed from relatives

  • The head, neck, body, hips and hind legs are restored by comparison with the nodosaur Europelta.
  • The arms, hands, feet and tail are restored by comparison with Sauropelta, whose proportions the published body outlines also borrow.

Still unknown

  • The complete arrangement of its armor.
  • Its skull shape and full body proportions.
  • Whether newer nodosaur armor from the same rocks belongs to Invictarx. It shares its surface texture but differs in the shape of its ridges.

Discovery timeline

  1. 2013Close relativeKirkland et al.
  2. 2018Named itMcDonald & Wolfe
  3. 2018Same rocksMcDonald, Wolfe & Dooley
  4. 2021Same rocksMcDonald et al.

Key papers

The research behind what we know of Invictarx

Close relatives

Other members of Nodosauridae

Sources: Wikidata