Updated

Updated · Sci.News · Jul 10

New 9mm Cargninia Jaw Pushes 225-Million-Year Lizard Relative Deeper Into Early Reptile Lineage

Updated

Updated · Sci.News · Jul 10

New 9mm Cargninia Jaw Pushes 225-Million-Year Lizard Relative Deeper Into Early Reptile Lineage

Q: This tiny reptile lived with early dinosaurs. What did its fossilized nerves reveal about its senses?

The fossilized nerve traces showed that *Cargninia enigmatica* likely sensed its surroundings much like modern lizards, snakes, and tuatara. Using micro-CT scans of the tiny jaw fossil, researchers reconstructed the branching pattern of the trigeminal nerve, a major nerve involved in facial and jaw sensation. They found that its layout closely matched that of living lepidosaurs. That similarity suggests this 225-million-year-old reptile had comparable sensory perception in the face and jaw region, helping it detect and respond to its environment in a broadly similar way. The finding was important not just for understanding its senses, but also for placing the animal on the reptile family tree. The nerve anatomy provided key evidence that *Cargninia* was an early lepidosauromorph relative, branching off before true lepidosaurs evolved.

1 articles · Updated · Sci.News · Jul 10

A partial 9 mm lower jaw from southern Brazil has given paleontologists the clearest view yet of Cargninia enigmatica, a tiny reptile that lived about 225 million years ago in the Late Triassic.
Micro-CT scans of the fossil—preserving 12 teeth and evidence for up to 18—mapped the trigeminal nerve canal, showing a branching pattern close to that of living lepidosaurs.
Computational phylogenetic analysis placed Cargninia consistently among non-lepidosaur lepidosauromorphs, indicating it split off before true lepidosaurs such as modern lizards, snakes and tuatara evolved.
The find sharpens a lineage previously known only from a single jaw fragment described in 2010, helping fill a sparse fossil record for the earliest stages of lizard and snake evolution.