Paleontologists have announced the discovery of a new genus and species of baracromian ichthyosaur, based on the fossilized skull found in the Água de Madeiros Formation, Portugal.
Gadusaurus aqualigneus. Image credit: Pratas e Sousa et al., doi: 10.4202/app.01199.2024.
The newly-identified species swam in the Early Jurassic seas approximately 193 million years ago.
Scientifically named Gadusaurus aqualigneus, the marine reptile was a small-sized ichthyosaur, with an estimated length of 2 m (6.6 feet).
“Ichthyosaurs were a group of Mesozoic reptiles best known for their re-adaptation to a marine environment,” said Dr. João Pratas E Sousa from the Universidade Nova de Lisboa and colleagues.
“They ranged in age from the Early Triassic to the Late Cretaceous, but the ichthyosaur fauna of the Early Jurassic is the most frequently preserved in the fossil record of Europe.”
“Although the remains of ichthyosaurs are quite abundant in marine deposits in some regions of Europe, their record is very scarce and fragmentary in southern areas such as the Iberian Peninsula (Portugal and Spain).”
The nearly complete skull of Gadusaurus aqualigneus — approximately 35.2 cm (13.9 inches) in length, in a flattened state — was discovered in 2021 in the Água de Madeiros Formation.
“The studied specimen was collected in mainland Portugal, in the São Pedro de Moel area,” the paleontologists said.
“Specifically, the block containing the fossil was discovered on the sands of Água de Madeiros beach, in the stream that forms the border between the municipalities of Marinha Grande and Alcobaça.”
“This locality is situated within the confines of the Lusitanian Basin, which is located on the western Iberian passive margin of the Atlantic Ocean, and provides an excellent marine record of the Lower Jurassic,” they added.
“The Lusitanian Basin is a north-south elongated basin, with borders defined by the Iberian Massif to the east and by the Variscan Berlenga Horst to the west.”
“The development of this basin occurred during the opening of the Atlantic Ocean, and it has undergone several rifting and sedimentary phases with deposits spanning from the Upper Triassic to the Upper Cretaceous.”
The team’s phylogenetic analysis recovered Gadusaurus aqualigneus as part of the ichthyosaur clade Baracromia, part of the Neoichthyosauria and Parvipelvia clades.
“The discovery of this specimen represents the most complete and best-preserved remains of an ichthyosaur described to date in the Iberian Peninsula,” the researchers said.
“As a result, it is also the first new species of this group of marine reptiles described in Iberia.”
“This specimen precedes the Toarcian Oceanic Anoxic Event that is theorized to have affected the lifestyle of later ichthyosaur genera.”
“It can be hypothesized that the transgressive events that occurred in this time period may have had similar effects on the lifestyle of this species, but further research is required.”
The discovery of Gadusaurus aqualigneus is announced in a new paper published online in the journal Acta Palaeontologica Polonica.
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J. Pratas e Sousa et al. 2025. A new ichthyosaur from the Lower Jurassic of Portugal (Iberian Peninsula). Acta Palaeontologica Polonica 70 (1): 179-192; doi: 10.4202/app.01199.2024
