Sauropelta edwardsorum SOR-oh-PEL-tah

"Lizard shield"

Sauropelta silhouette — silhouette · Marie Aimée ALLARD (CC0) via PhyloPic

Length: 5.2 m (17.1 ft) — About 5.2 m long, ~1.5 tonnes — armored but no tail club.
Period: Early Cretaceous (115–108 Mya)
Place: North America · Wyoming · Montana
Food: Herbivore — Low-growing plants, probably ferns and tough cycad fronds.
Clade: Nodosauridae Dinosauria Ornithischia Thyreophora Ankylosauria Ankylosaurs without the tail club.

An Early Cretaceous "lizard shield" armored in bony plates with long spines jutting from its neck.

Sauropelta was a nodosaurid — an ankylosaur cousin that traded the heavy tail club for long shoulder spikes. The shoulders carried two pairs of sideways-pointing spikes that probably warded off attackers from the side. Unlike Ankylosaurus, the tail was flexible and unarmored at the tip.

More about Sauropelta

Discovery

Named by John Ostrom · 1970 · Cloverly Formation, North America (specimens from Wyoming, Montana, and possibly Utah; the holotype came from Big Horn County, Montana)

In the early 1930s Barnum Brown collected the holotype, a partial skeleton, from the Cloverly Formation in Big Horn County, Montana, inside the Crow Indian Reservation. Expeditions led by John Ostrom in the 1960s recovered more specimens, and in 1970 Ostrom coined the genus to include remains from both efforts.

The name means "lizard shield," a reference to its bony armor. It comes from Greek: sauros ("lizard") and pelte ("shield").

John Ostrom. A paleontologist at Yale University's Peabody Museum of Natural History who led 1960s expeditions to the Cloverly Formation and formally named the genus Sauropelta in 1970.

Did <em>Sauropelta</em> actually leave the footprints attributed to it?

Tracks named Tetrapodosaurus borealis were reported in 1932 by Charles Mortram Sternberg, who attributed them to ceratopsian dinosaurs. In 1984 Kenneth Carpenter re-examined them and argued they were made by ankylosaurs instead, concluding they were probably Sauropelta footprints. The attribution is an interpretation rather than a direct match to body fossils.

For the curious → Why does its skull roof look so seamlessly fused?

The top of the skull was very thick and covered in flat bony plates so tightly fused that no sutures appear, unlike in relatives such as Panoplosaurus and Pawpawsaurus. The text notes this seamless look could be a real feature, but it may also be an artifact of preservation or preparation.

What we know

Long sideways-pointing shoulder spikes — the longest of any nodosaur.
Skin armor across the back, but no tail club.
Lived alongside Deinonychus in the Cloverly Formation.
Wide barrel-shaped body for plant fermentation.

What we guess

Whether the shoulder spikes were primarily defensive or also for display.
How it survived attacks by Deinonychus — possibly by crouching to expose only its armored back.
Whether nodosaurids and ankylosaurids descended from a common armored ancestor or evolved armor separately.