Altispinax

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Altispinax means “with high spines.” It is a large predatory dinosaur from the Early Cretaceous period (about 140–133 million years ago) found in what is now East Sussex, England. The animal is known from three tall-spined back vertebrae (the holotype NHMUK PV R 1828) found in the Hastings Bed Group near Battle.

The bones were discovered by Samuel Beckles in the 1850s and sent to the paleontologist Richard Owen, who described them in 1856. Owen initially linked the vertebrae to Megalosaurus bucklandii, contributing to decades of confusion about where these fossils fit in the dinosaur family tree.

In 1923 Friedrich von Huene created the genus Altispinax for Megalosaurus dunkeri and based it on the tall-spined vertebrae. Since then, many scientists proposed different names for the same vertebrae, such as Acrocanthosaurus altispinax and Becklespinax altispinax, while others suggested Altispinax altispinax or Altispinax lydekkerhueneorum. For a long time the classification remained tangled.

A major resolution came in 2016 when Michael Maisch re-examined the history. He argued that Huene’s Altispinax dunkeri was named for the tall vertebrae, and that the later names based on the same vertebrae are junior objective synonyms. In other words, Altispinax dunkeri is the correct name for this fossil, and the other vertebrae-based names refer to the same specimen.

There were also other species once placed in Altispinax, such as Oweni (later given to Valdoraptor) and Parkeri (later treated as Metriacanthosaurus parkeri). The exact relationships of Altispinax within theropods remained uncertain, with different scientists placing it in various groups over the years. Today most researchers treat Altispinax as a theropod within the large group Tetanurae, but its precise relatives are unknown because the fossils consist only of three tall-spined vertebrae.

The three vertebrae show neural spines about 35 centimeters tall, with distinctive rugosities on the spines. Some debate exists about whether the spines were fused or injured, but later findings in other dinosaurs have provided context for these features. Overall, Altispinax is best understood as a tall-spined predator from a well-lit chapter of early cretaceous England, with a complicated patchwork of naming that modern work has helped clarify.