About 165 million years ago, in a alluvial coastal plain of what is now Morocco, one of the most registered extreme dinosaurs lived, profusely adorned with armor and spikes, some up to one meter long, unlike any other known creature.
Researchers described on Wednesday the extensive fossilized remains found in the Atlas mountain range, near the Moroccan city of Boulemane, of a dinosaur of the Jurassic period called Spicomellus. With approximately four meters long and one weight between one and two tons, Spicomellus is the oldest known member of a group of battlesuries shaped like tank called anquilosaurs, chomber herbivores and slow movements that walked on four legs.
“The Spicomellus armor is surprisingly strange, different from that of any other dinosaur, or any other living or dead animal, which we have discovered,” said Vertebrates paleontologist Richard Butler, from the University of Birmingham (England), a collide of the research published in the journal Nature.
“Not only had a series of long and sharp spikes in each rib, something unknown in other animals, but also had spikes as long as golf sticks that stood out forming a necklace around the neck,” Butler added.
The extravagant armor could have fulfilled a double function: defense against large carnivorous dinosaurs and exhibition to attract couples.
“The armor certainly had some defensive function, but it is difficult to imagine how the spikes one meter around the neck were used to defend themselves. They seem a huge exaggeration,” Butler concluded.
In current animals, structures that do not usually have an obvious function and that seem annoying to transport, such as the antlers of a deer or the tail of a peacock, are usually associated with sex, according to the paleontologist of vertebrates and main author of the study, Susannah Maidment, of the Natural History Museum of London.
“They could be used in courtship or territorial exhibitions, or to fight against members of the same species during competitions to mate. The Spicomellus armor is totally impractical and would have been somewhat annoying in dense vegetation, for example. Therefore, we believe that it is possible that the animal develops a armor so elaborate for some type of exhibition, perhaps related to the mounts,” added Maidment.
Read more: they reveal a dinosaur fossil of 166 million years
Spicomellus armor launches unknowns about the species
While fossils do not represent a complete skeleton (the head was among the missing parts), the partial remains provided a good understanding of Spicomellus. This dinosaur was only known by a single rib fragment described in 2021, before these fossils were found in 2022 and 2023.
His back was covered with short spikes, due to the ribs with spikes on the upper surface. It had a bone necklace with plates and two pairs of spikes that were projected out of the neck, including an 87 cm long that was probably even longer in life. He also had a pelvic shield and two large spikes that were projected out over the hips.
The distinctive vertebrae of the puffed tail suggested that Spicomellus possessed a weapon at the tip of the tail to defend against predators, perhaps a mace or spikes of some kind, although none was found among the remains.
These fused tail vertebrae had only been found previously in anquilosaurs with weapons in the tail. This would indicate that the weapons in the tail appeared in the ankylouries about 30 million years before what was believed.
The ankyosaurs were among the most successful herbivorous dinosaurs. They are closely related to another group of herbivores called stegosaurus, which boasted of bone plates on the back and a pointed tail.
Both groups arose during the Jurassic. But the anquilosaurs survived the stegosaurus, thriving until an asteroid hit the earth 66 million years ago, at the end of the Cretaceous, ending the era of dinosaurs. The best known member of the group, the Ankylosaurus, was larger than the Spicomellus, with approximately 8 meters long, and inhabited western North America during the sunset of dinosaurs. His armor, which included a formidable maza in the tail, protected them from predators such as Tyrannosaurus.
The first members of the dinosaur groups usually have quite simple body structures compared to their posterior counterparts. The Spicomellus demonstrates that this was not the case of anquilosaurs.
The Spicomellus armor is much more elaborate than that of the posterior ankylouries, and no posterior anquilaurus presents pointed ribs.
The surprising thing is that the most elaborate anquilosour armor of all time is in the oldest member of the group. Perhaps the simplest armor in subsequent species reflects a transition to a mainly defensive function due to the greater predation pressure in the Cretaceous, when predators reached an exceptional size, said Butler.
With Reuters information
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