A large lamniform shark from the Aptian of Villa de Leiva (Boyacá, Colombia), based on the first Lower Cretaceous shark specimen preserving both teeth and vertebrae

We describe a new specimen of a lamniform shark from the upper Aptian of the Arcillolitas abigarradas Member of the Paja Formation of Villa de Leiva (Colombia). It represents the first lamniform shark specimen from the Lower Cretaceous with both teeth and vertebrae preserved. The specimen consists of several disarticulated but well-preserved teeth and well-preserved partially articulated vertebral centra, denticles and soft tissues. We refer the specimen to Protolamna ricaurtei, a species recently erected from a specimen found in the same formation. It is a lamniform shark characterized by proportionally small tearing-type teeth with small triangular main cusp, two pairs of small triangular lateral cusplets, and massive bilobated roots. The specimen represents a mature individual to be 6.65 m in total length, making it the oldest record of a gigantic lamniform. This specimen is the first evidence that not all macrophagous lamniforms follow the linear function relating crown height to total body length. Our taphonomic analysis indicates that the specimen must have rapidly reached an anoxic bottom, with low benthic activity, gentle currents, and with microbial mats that facilitated the rapid phosphatization of the soft tissues. Based on the preserved anatomy, we propose that Protolamna ricaurtei was a relatively slow but active swimmer feeding in tropical near-shore areas over small preys such as bony fishes, small sharks, squids, and crustaceans.