Description and Classification

The only known species is Iberospinus natarioi, named in honor of Carlos Natário, the amateur paleontologist who discovered the original fossil. Iberospinus was a medium-sized, carnivorous dinosaur that walked on two legs. Like other members of the Spinosauridae family—a group that includes well-known dinosaurs such as Spinosaurus and Baryonyx—it possessed an elongated, crocodile-like snout and conical (cone-shaped) teeth. These features suggest it was well-adapted for hunting fish. Although the known fossils of Iberospinus are incomplete, consisting of parts of the lower jaw, teeth, tail bones (vertebrae), a hip bone (pubis), and foot bones, they provide important clues about its appearance. The neural spines (bony projections) on its tail vertebrae were likely tall, contributing to a distinctive profile, though probably not forming the massive sail seen on its larger relative, Spinosaurus.

Iberospinus is classified as a theropod dinosaur within the family Spinosauridae. This diverse family also includes other notable genera like Suchomimus from Africa and Irritator from South America. Spinosaurids are recognized for adaptations that point to a semi-aquatic lifestyle, meaning they likely spent a significant amount of time in or near water. The precise evolutionary relationships of Iberospinus within the Spinosauridae family are still under investigation, but its discovery provides valuable information about the early evolution and geographical distribution of these specialized predators in Europe.

Distinguishing Features

Iberospinus can be distinguished from other spinosaurids by several unique anatomical details observed in its fossils. These features helped scientists recognize it as a distinct genus:

• A specific pattern of grooves and openings for nerves and blood vessels on the outer surface of its dentary (the main bone in the lower jaw).
• A Meckelian groove, which is a channel on the inner side of the lower jaw, that runs straight and does not split into two branches as it does in some other spinosaurids.
• Evidence suggesting that some tooth sockets in its jaw held more than one replacement tooth, ready to erupt if the active tooth was lost.
• Unique shapes and characteristics in its pubis (one of the bones forming the hip) and its caudal (tail) vertebrae.

Paleoenvironment and Diet

Iberospinus inhabited the coastal regions of what is now Portugal during the Barremian age of the Early Cretaceous period. The Papo Seco Formation, where its fossils were unearthed, represents an ancient environment characterized by river deltas, lagoons, and wetlands. This diverse habitat would have supported a rich variety of life, including other dinosaurs like iguanodontians and different types of theropods, as well as crocodiles, turtles, and abundant fish.

Consistent with other spinosaurids, Iberospinus is believed to have been primarily a piscivore, meaning its diet mainly consisted of fish. Its long, narrow snout and numerous sharp, conical teeth were ideal for grasping slippery aquatic prey. It is also plausible that Iberospinus was an opportunistic feeder, potentially supplementing its diet with small land animals or scavenging on carcasses when available. Its lifestyle was likely closely tied to the aquatic environments it lived in, similar to modern-day animals like crocodiles or large fish-eating birds.

Significance and Ongoing Research

The discovery of Iberospinus is significant as it expands our knowledge of spinosaurid diversity, particularly in the Iberian Peninsula during the Early Cretaceous. It demonstrates that this group of dinosaurs was more varied in Europe than previously understood. The identification of Iberospinus also underscores the importance of re-examining existing fossil collections, as its bones were recognized as a new type of dinosaur after initially being assigned to a different genus.

Research on Iberospinus is ongoing. Paleontologists are keen to uncover more complete fossil material, which would offer a more detailed understanding of its full anatomy, overall size, and how it moved. Further detailed studies of the known fossils will help to clarify its precise evolutionary relationships with other spinosaurids, such as Baryonyx from England and Spain, and Spinosaurus from North Africa. This continuing research contributes to a broader understanding of how spinosaurid dinosaurs evolved and dispersed across different continents during the Mesozoic Era, and helps reconstruct the ancient ecosystems of the Iberian Peninsula.