A tiny dinosaur has been found in Spain

An international team of palaeontologists has described a new species of dinosaur - Foskeia pelendonum, one of the smallest known ornithopods of the Early Cretaceous period. It was less than half a metre long, but its skull anatomy was unexpectedly complex and evolutionarily advanced. The discovery helps fill a multi-million-dollar gap in the evolutionary history of European herbivorous dinosaurs.

The fossils were found at the Vegaheta site in the province of Burgos in northern Spain. The study, led by Paul-Emile Dieudonné of the National University of Rio Negro, Argentina, is published in the journal Papers in Palaeontology.

According to Dieudonné, the first thing that strikes scientists when looking at Foskeia is its tiny size.

"This adult animal was incredibly small, yet it possessed a skull with unexpected anatomical innovations," he notes.

The find includes the remains of at least five individuals first discovered by palaeontologist Fidel Torcida Fernández-Baldor of the Salas de los Infantes Dinosaur Museum. From the outset, scientists noticed the exceptional miniaturisation of the bones, but further study revealed that the significance of the find goes far beyond size.

The genus name Foskeia is derived from ancient Greek words meaning "light" and "feed", reflecting the animal's low weight and lifestyle. The species name pelendonum refers to the Pelendonians, a Celtiberian tribe that inhabited the region in ancient times.

Despite its diminutive size, Foskeia pelendonum displays a highly specialised skull structure. According to the scientists, the reduction in body size did not mean evolutionary "simplicity" at all.

"Miniaturisation did not lead to primitiveness - the skull of this dinosaur is strange and highly derived," stresses Marcos Beserra from the National University of Córdoba. His colleague Thierry Tortosa notes that the find helps close a gap of about 70 million years in the evolutionary record of ornithopods.

The researchers emphasise that Foskeia is not a "smaller version of iguanodon". It is a fundamentally different line of development that forces a rethinking of existing evolutionary schemes.

Histological analysis of the bones, led by Koen Stein from the Free University of Brussels, showed that the largest specimen found was a sexually mature adult. The bone microstructure indicates a relatively high metabolism - comparable to that of small birds or mammals.

This is particularly important for a valid comparison of Foskeia with other species, as in young individuals the anatomy can change significantly as they grow.

The phylogenetic analysis placed Foskeia next to Australian Muttaburrasaurus within the Rhabdodontomorpha group and expanded the view of the European lineage of Rhabdodontia. In addition, the analysis again supported the hypothesis of the existence of a large evolutionary group Phytodinosauria uniting herbivorous dinosaurs.

Despite its small size, Foskeia possessed specialised teeth and probably changed posture as it grew, relying on sudden bursts of speed to move through dense forests.

The authors say the finding demonstrates that evolution has experimented as radically with small forms as it has with giants. It is such "inconspicuous" species that could play a key role in understanding the history of dinosaurs.