Rare fossil discovery reveals earliest ancestor of armored dinosaurs

Scientists have just published a new analysis in the journal Nature, revealing the most complete specimen ever of Spicomellus afer - the oldest known armored dinosaur.

The fossil was discovered in the Middle Atlas Mountains of Morocco and possesses a strange armor never seen in any living or extinct animal.

The research team, led by Dr Susannah Maidment of the Natural History Museum London and the University of Birmingham, analysed fossil bone fragments excavated from Middle Jurassic rock layers near the Boulemane area.

The discovery began when a local farmer reported finding strange bones in the flood.

The archaeological team then went to the site - with the exact location kept secret to protect the site - and collected more specimens.

The fossil specimen includes vertebrae, ribs, pelvic bones and many pieces of osteoderms, allowing scientists to relatively reconstruct the shape of this dinosaur despite the incomplete skeleton.

Most notable is the sturdy bone “necklace” surrounding its neck with 10 large spikes – the longest of which measured 87 cm and may have been longer in life.

In addition, the hips also have large spines, the pelvic shield has alternating long and short spines, and the ribs carry 3-4 sharp spines - a structure never seen in any other species.

“The armour of Spicomellus is truly extraordinary, unlike any other dinosaur – or any other creature ever discovered,” said Dr Richard Butler, a palaeontologist at the University of Birmingham, who co-led the research. “We even had to do a CT scan to make sure it wasn’t a fake, like someone glued spikes onto a bone ring.”

The discovery also demonstrates that key ankylosaur evolutionary features, particularly the tail weapons, arose some 30 million years earlier than previously thought. Traces of the tail weapon structures, along with the vertebrae fused into the hilt, suggest that the “tail club” – a prominent weapon in later ankylosaur species – began to form during the Middle Jurassic.

In addition to their defensive function, scientists believe these large spines may play a role in display or mating.

“It’s hard to believe that the nearly meter-long spines around the neck are for defense only,” Dr. Butler said. “They are most likely for attracting mates.”

Dr Maidment said that, similar to today’s antlers or peacock tails – cumbersome but ‘showy’ structures – Spicomellus’ large spines may have served a similar role. Later, as predation pressure increased in the Cretaceous, ankylosaurs evolved simpler, more defensive-focused armour.

Spicomellus afer lived about 165 million years ago, in what was once the supercontinent Gondwana - today Morocco. This species was about 4 meters long, weighed between 1.5 and 2 tons, had a wide body, short legs, moved slowly and ate plants.

Previously, Spicomellus was only known from a single rib fragment with spikes attached (discovered in 2021), but the new specimen helps scientists reconstruct a dinosaur with an extremely special "decoration" - from the neck, ribs to hips are covered with sharp spikes.

“We will continue to excavate this unique and previously unknown ecosystem in the Middle Atlas,” said Dr Maidment. “We hope to find more unusual dinosaurs – and possibly the entire skeleton of Spicomellus.”

(Vietnam+)

Source: https://www.vietnamplus.vn/phat-hien-hoa-thach-hiem-he-lo-to-tien-som-nhat-cua-loai-khung-long-boc-giap-post1059085.vnp