Trematosaurus: a long-snouted temnospondyl of the Early Triassic

Trematosaurus brauni was a long-snouted temnospondyl from the Early Triassic of central Germany. Fossils from Merkel’s Quarry near Bernburg include a substantial series of skulls and natural casts, making the head much better known than the rest of the animal. A modern osteological study revised the palate, lower jaw and braincase and examined growth-related variation. The genus gives the ancient amphibian catalogue a well-documented example of a trematosaurid whose cranial evidence far exceeds its postcranial record.

Quick facts

A name from Bernburg

Hermann Burmeister named Trematosaurus brauni in 1849 from fossils collected near Bernburg in what is now Saxony-Anhalt, Germany. Merkel’s Quarry produced material over decades, beginning in the 1840s. The skull collection became central to the study of the genus and later gave its name to Trematosauridae.

Preservation is unusual. Groundwater dissolved much of the original bone, leaving internal casts that record the cavities and surfaces of the skull. Other specimens retain bone. A cast can preserve useful shape, but it does not provide every surface detail; researchers distinguish the anatomy visible in a mould from features that require original bone.

The 2019 osteological study redescribed the skull roof, palate, mandible, occiput and braincase. It brought old museum material into a modern comparative framework. These specimens are not a single associated skeleton: their value comes from a large cranial sample, not from preserving each part of the body together.

A long skull and its growth pattern

The skull is elongated and narrow, with the orbits positioned well behind the snout. Numerous teeth line the jaws, and grooves on the skull bones mark the lateral-line canals. This combination fits an aquatic predator that could detect water movement. It does not identify a particular prey species or prove a specific strike technique.

The size range of the skull sample allows researchers to compare smaller and larger individuals. As skull length increases, the orbits become proportionally smaller and the cranium becomes relatively narrower. The interorbital region and the preorbital part do not show all the changes expected from a simple widening pattern. Growth explains some differences among specimens, but not every difference can be assigned to age without other evidence.

Deformation and preservation complicate measurements. A crushed skull or a cast of a dissolved bone may not retain the original proportions perfectly. Taxonomic comparisons therefore rely on multiple characters and on the condition of each specimen, rather than treating every difference in outline as biological.

What can be said about the body?

Unlike the skull, the postcranial skeleton is poorly represented by securely associated material. A commonly repeated body length near two metres is a reconstruction based on skull size and comparison with related trematosaurids. It is not the measured length of a complete individual. The same limitation applies to a detailed tail profile or precise limb proportions.

Small limbs and a long body are often shown in reconstructions, with the tail providing most forward thrust. That is a reasonable model for a water-associated temnospondyl, but it is not directly documented by a complete Trematosaurus skeleton. Lateral-line grooves and the shape of the skull provide firmer evidence for aquatic habits than any claim about its exact swimming stroke.

Early Triassic setting and limits

The Bernburg fossils come from the Middle Buntsandstein, within the Olenekian Age of the Early Triassic. The rocks formed in a continental sedimentary system. The quarry assemblage may combine remains transported from nearby settings, so a concentration of skulls does not prove that a large group lived or died together at that precise spot.

The broader Early Triassic followed the end-Permian mass extinction. Trematosaurids spread across multiple regions, but that pattern does not demonstrate seasonal migration by T. brauni. A reconstruction can show a long-snouted amphibian in fresh water, while its colours, soft tissues, exact size and prey remain interpretive or unknown.