''Iberospinus'' or (meaning " Iberian spine") is an extinct genus of spinosaurid dinosaur from the

Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pro ...

( Barremian) Papo Seco Formation of Portugal. The genus contains a single species, ''I. natarioi'', known from several assorted bones belonging to one individual. ''Iberospinus'' represents one of three known spinosaurid taxa from the Iberian Peninsula, the others being ''

Vallibonavenatrix ''Vallibonavenatrix'' (meaning "Vallibona huntress" after the town near where its remains were found) is a genus of spinosaurid dinosaur from the Early Cretaceous (Barremian) Arcillas de Morella Formation of Castellón, Spain. The type and onl ...

'', and '' Camarillasaurus''. It is important for its implications of the geographical origin of Spinosauridae and the suggested presence of an at least semi-aquatic lifestyle early in the evolution of this clade.

Discovery and naming

The first fossil material was discovered in 1999, with additional expeditions from 2004 to 2008. After being described as a specimen of '' Baryonyx'' in 2011, it was realised to have been a unique species in 2019. Additional material was discovered in a June 2020 expedition, after which ''Iberospinus'' was described as a new genus and species in 2022 by Octávio Mateus and Darío Estraviz-López. ''Iberospinus'' is currently known from dentary fragments, teeth, an incomplete right scapula, partial dorsal and

caudal Caudal may refer to: Anatomy * Caudal (anatomical term) (from Latin ''cauda''; tail), used to describe how close something is to the trailing end of an organism * Caudal artery, the portion of the dorsal aorta of a vertebrate that passes into the ...

vertebrae,

rib In vertebrate anatomy, ribs ( la, costae) are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the ches ...

fragments'','' a partial pubis, two incomplete calcanea, and a pedal ungual phalanx''.'' All of the material belongs to one individual. The holotype material represents one of the most complete spinosaurid specimens in the world. Of the generic name, "''Iberospinus''," "ibero," is derived from ''Iberia'', a Roman name for the Iberian Peninsula, while the Latin "spinus," or means spine, after the elongated neural spines of related spinosaurids. The specific name, "''natarioi'', " honors

Carlos Natário Carlos may refer to: Places ;Canada * Carlos, Alberta, a locality ;United States * Carlos, Indiana, an unincorporated community * Carlos, Maryland, a place in Allegany County * Carlos, Minnesota, a small city * Carlos, West Virginia ;Elsewhe ...

, the discoverer of the holotype.

Description

The dentary (lower jaw) of ''Iberospinus'' shows an intricate neurovascular system that would connect the teeth and the external foramina. A series of replacement teeth are also preserved in the dentary. Characteristics of the bones, especially in the tail and pedal ungual phalanx, indicate a possible semi-aquatic lifestyle, though the extreme features in some related spinosaurines are not seen. Iberospinus Scapula

The following autapomorphies distinguish ''Iberospinus''. The dentary bone contains a single foramen within the Meckelian sulcus and has a straight ventral edge instead of curved as in most other spinosaurids. Laminae are present in the pleurocoelic depression of the mediodistal tail vertebrae. The shoulder blade has a straight anterior rim without a protruding acromion and a coracoidal contact occupying the entire ventral surface. The pubic apron is thick throughout the entire length of the pubic shaft. There is a mound-like eminence in the proximal lateral portion of the pubic bone.

Classification

''Iberospinus'' was recovered within the Spinosauridae, outside of both the

Baryonychinae Baryonychinae is an extinct clade or subfamily of spinosaurids from the Early Cretaceous (Valanginian-Albian) of Britain, Portugal, and Niger. In 2021, it consisted of six genera: ''Ceratosuchops'', ''Cristatusaurus'', ''Riparovenator'', ''Suchomi ...

and the Spinosaurinae. However, Mateus & Estraviz-López (2022) explain that the fossil material shows some characteristics of baryonichines, suggesting a closer relation to the group. An adjusted cladogram after the describing authors is shown below:

Palaeoenvironment

The Papo Seco Formation of Portugal where ''Iberospinus'' is known from is composed of

marl Marl is an earthy material rich in carbonate minerals, clays, and silt. When hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae. Marl makes up the lower part o ...

, representing a lagoon environment. Other dinosaur remains from the area include fragments tentatively assigned to ''Mantellisaurus'', a macronarian sauropod, and ''Megalosaurus''. Most of the bones of ''Iberospinus'' specimen ML1190 were damaged, and some scratches may be marks from small scavengers. The specimen's disarticulation indicates it was transported from a more-terrestrial environment (since many bones are missing), but those found were close together.

References

{{Taxonbar, from=Q110939377 Spinosaurids Fossil taxa described in 2022 Fossils of Portugal Barremian life Early Cretaceous dinosaurs of Europe