New Dinosaur Species Reveals Radical Evolution in Ankylosaurs

A newly discovered dinosaur species, Spicomellus afer, is transforming our understanding of ankylosaur evolution. Researchers unearthed a significant collection of bones in Morocco, shedding light on the physical characteristics of this prehistoric creature, which lived during the Cretaceous period. This find provides a clearer picture of how these armored dinosaurs developed their unique features, including an array of impressive spines and a distinctive tail structure.

Ankylosaurs are known for their squat, armored bodies and formidable tails, which served as defense mechanisms against predators. Previously, knowledge about their origins was limited due to sparse fossil evidence, with Spicomellus previously represented by only a single partial rib. The new fossils reveal that the armor and spikes of Spicomellus were far more elaborate than those of later ankylosaurs, suggesting a different evolutionary pathway.

Revolutionary Characteristics of Spicomellus

The fossils indicate that Spicomellus afer featured massive rows of meter-long spikes and bony collars, akin to a fusion of punk rock aesthetics and flamboyant glam. Unlike the smaller, solid spikes typical of later ankylosaurs, Spicomellus boasted a back covered with sharp spines, with some extending nearly a meter in length. Researchers found that each rib had the potential to generate up to six individual spikes.

The most striking feature was found on the neck, where fused osteoderms formed an enormous half-collar of bone. This collar extended into multiple long spikes, a characteristic not seen in any other known ankylosaur. The discovery team emphasized, “No known ankylosaur possesses any condition close to the extremely long pairs of spines on the cervical half-ring of Spicomellus.”

The tail also exhibited unique adaptations, with vertebrae showing signs of a weaponized structure. Researchers highlighted that the new specimen reveals “extreme dermal armour modifications unlike those of any other vertebrate, extinct or extant.”

Implications for Ankylosaur Evolution

The unusual characteristics of Spicomellus afer pose challenges for classification within the ankylosaur family tree. The findings suggest that Spicomellus may represent an early branch of the ankylosaur lineage, though the lack of significant examples from that time makes this conclusion tentative.

This discovery disrupts established theories regarding ankylosaur evolution. Previously, researchers posited that the club-like tails found in some Cretaceous species evolved later in response to predation pressure. The presence of these tail adaptations in Spicomellus implies they may have originated much earlier than previously thought.

Additionally, the study challenges the belief that armor became more elaborate over time as predators grew larger. Instead, the findings suggest that the less ornate armor of later ankylosaurs was sufficient for protection. Researchers now propose that the extravagant features of Spicomellus may have evolved for mating displays rather than solely for defense. They noted, “Structures with limited obvious functionality and that are energetically expensive to produce tend to be sexually selected and function for display or combat.”

To refine the understanding of ankylosaur evolution, further discoveries of species from earlier periods are essential. Such findings could illuminate the evolutionary pathways that led to the distinctive features observed in this remarkable group of dinosaurs. The study, published in Nature, underscores the need to reevaluate long-held assumptions about these prehistoric creatures, expanding the narrative of their evolutionary history.