Ahshislepelta (AH-shiss-leh-PEL-tah; “Ahshisłpah’s shield”) is a genus of armored dinosaur known as an ankylosaurid. It lived during the Late Cretaceous period, about 75 million years ago, in what is now New Mexico, USA. The name refers to the Ahshisłpah Wash, a geological feature in the area where its fossils were discovered, combined with the Greek word “pelta,” meaning shield. Ahshislepelta was first described by paleontologists Michael E. Burns and Robert M. Sullivan in 2011. Our knowledge of this dinosaur comes from a partial skeleton that includes parts of the shoulder, forelimb, backbone, and many pieces of its bony armor.
Description and Classification
Ahshislepelta was a medium-sized ankylosaur, estimated to be about 4 to 5 meters (13 to 16 feet) long and weighing around 1 to 2 metric tons (1.1 to 2.2 short tons). Like other ankylosaurs, it was a heavily built, four-legged plant-eater protected by an extensive covering of bony plates called osteoderms embedded in its skin. These osteoderms varied in size and shape, with some being large and featuring keels (ridges), providing a strong defense against predators such as tyrannosaurids that lived at the same time.
Ahshislepelta belongs to the family Ankylosauridae, a group of dinosaurs known for their broad bodies, extensive bony armor, and often, heavy tail clubs (though a tail club has not definitively been found for Ahshislepelta itself). Within this family, its exact relationships are still being studied, but it is considered part of a group of North American ankylosaurs called anodontosaurins. It shares some features with other ankylosaurs from the same time period and region, such as Nodocephalosaurus and Ziapelta, which were also found in New Mexico.
Distinguishing Features
Scientists can identify Ahshislepelta by several specific characteristics found in its bones and armor. These include:
- A coracoid (a bone in the shoulder) that is longer than it is wide.
- A unique ridge, known as the scapular spine, located on a part of its scapula (shoulder blade) called the acromion process.
- A humerus (upper arm bone) with a particularly prominent deltopectoral crest, which is the area where strong arm muscles would have attached.
- Osteoderms (bony armor plates) that are large, feature a keel (a raised ridge), and some of which have a distinct hollow base.
Paleoenvironment and Diet
Ahshislepelta lived in an environment that, during the Late Cretaceous, was a warm coastal plain with many rivers, swamps, and lush forests. This ancient landscape is preserved in the rocks of the Kirtland Formation in New Mexico. This diverse ecosystem supported a wide variety of life. Other dinosaurs that shared this habitat included horned dinosaurs like Pentaceratops, duck-billed dinosaurs such as Parasaurolophus, and large carnivorous dinosaurs like Bistahieversor. The presence of other ankylosaurs like Nodocephalosaurus and Ziapelta in the same formation suggests that this area could support multiple types of armored dinosaurs.
As an ankylosaur, Ahshislepelta was a herbivore. Its low-slung body suggests it fed on low-growing vegetation. Although teeth specific to Ahshislepelta have not been found, related ankylosaurs had teeth suited for stripping leaves from plants. It likely ate plants such as ferns, cycads, and early flowering plants that were common in its environment.
Significance and Ongoing Research
The discovery of Ahshislepelta has helped paleontologists learn more about the variety of ankylosaur dinosaurs that roamed North America, especially in the southern part of the ancient continent of Laramidia (which is now the western part of North America). It provides important clues about how these armored dinosaurs evolved and spread across different environments. Ahshislepelta is one of several ankylosaur species found in New Mexico’s San Juan Basin, highlighting this region as an important area for ankylosaur diversity during the Late Cretaceous.
Ongoing research continues to explore Ahshislepelta’s place within the ankylosaur family tree. Scientists study its fossils by comparing them to those of other ankylosaurs to better understand its unique features and evolutionary relationships. While its exact classification and distinctiveness relative to other ankylosaurs are still topics of scientific discussion, each fossil find helps build a more complete picture of dinosaur life. Future discoveries of more complete skeletons would greatly aid in our understanding of this fascinating armored dinosaur.