Liliensternus: a Triassic predator known from mixed remains

Liliensternus liliensterni was a large-bodied early theropod from Late Triassic Thuringia in Germany. It lived during the Norian, probably around 215–208 million years ago, and moved on two hind legs. The genus is known from a mixed collection of incomplete bones representing at least two individuals. Parts of the skull and jaws, vertebrae, girdles and limbs survive, making it one of the better documented European theropods of its age, though no complete skeleton is known. Its profile belongs in the dinosaur catalogue with its disputed relationships and missing anatomy clearly marked.

Quick facts

A name honouring a Thuringian collector

The genus commemorates Hugo Rühle von Lilienstern, a German physician and fossil collector who built a museum at his castle in Bedheim. His work helped bring attention to the Triassic vertebrates of Thuringia. The species name liliensterni repeats his surname, so both parts of the scientific name honour the same person.

The fossils were collected in 1932–1933 near Großer Gleichberg, close to Römhild. They came from the upper part of the Arnstadt Formation. Older accounts often called the interval Knollenmergel and compared it with the Trossingen Formation. Those historical labels reflect changes in regional stratigraphic terminology; they do not identify a separate type locality.

Friedrich von Huene described the bones in 1934 as Halticosaurus liliensterni. The type material of Halticosaurus itself proved too fragmentary and difficult to diagnose for a stable grouping. In 1984, Samuel Welles placed Huene's species in the new genus Liliensternus.

Welles proposed the larger individual as a lectotype, but the bones had been mixed and could not be assigned confidently to separate animals. Researchers later treated the collection MB.R.2175 more cautiously as a series of syntypes representing at least two individuals. The fossils are held by the Museum für Naturkunde in Berlin. This history matters because the apparent anatomical completeness of a composite collection is not the same as a single articulated skeleton.

Classification among early theropods

The theropod identity of Liliensternus is secure, as is its placement among Neotheropoda. The uncertainty concerns the branch near the base of that large radiation. Traditional classifications placed it in Coelophysoidea, near Coelophysis and related early forms. Features of the neck vertebrae, pelvis and hind limbs contributed to that view.

Some current analyses retain it as a non-coelophysid coelophysoid. Others place it on the stem of Averostra, the lineage that includes ceratosaurs and tetanurans, but outside Averostra itself. The exact result can change with the anatomical characters and comparison taxa included. Its uncertain position does not make it a tyrannosaur, a late theropod family member or an ancestor of any one later genus.

A French species named Liliensternus airelensis in 1993 was reassessed because its supposed distinguishing features were not unique. In 2007 it was moved to the separate genus Lophostropheus. Only L. liliensterni is currently recognised in Liliensternus. This is a useful example of why similar age and a once-shared genus name do not guarantee that fossils represent the same animal.

What is preserved

MB.R.2175 includes fragments of upper and lower jaws with teeth, neck, trunk, sacral and tail vertebrae, ribs, parts of the shoulder and pelvic girdles, and bones from the limbs. Both larger and smaller elements occur, but it is difficult to assign every bone to one individual or the other. The collection therefore records more anatomy than a single isolated tooth but less than a complete skeleton.

The skull is especially incomplete. There is not enough material to restore its full profile or count all the teeth with confidence. A familiar high-crested head in a museum model or illustration adds assumptions beyond the surviving skull fragments. The axial skeleton and limbs offer firmer information about body support and movement than the upper skull does.

Some vertebrae have pneumatic openings, features associated with air-filled spaces in the skeleton of early theropods. Their neck vertebrae also show a pair of lateral depressions and bony laminae used in anatomical comparisons. The pelvis and femora add characters to phylogenetic analyses. Several bones still carry unfinished sutures between vertebral centra and neural arches; the sacrum has only two clearly joined vertebrae. These details have been interpreted as signs that the represented animals may not have been fully mature, though the mixed collection prevents a precise growth series.

Teeth and bones from other German and Swiss localities have sometimes been referred to the genus. Most are too isolated to verify that assignment. The strongest geographic evidence remains the type locality in Thuringia.

Size, anatomy and movement

Known individuals are commonly reconstructed at about 5–5.5 metres long and 120–200 kilograms. These estimates do not describe a complete adult measured from nose to tail. If the collection includes immature animals, a fully grown individual could have been larger, but the maximum adult size is unknown. Proposed lengths of 7–9 metres rely on fragmentary material that may belong to a close relative rather than Liliensternus.

The animal had a comparatively light build for a predator of that length. A long tail balanced the trunk. One measured femur is about 44 centimetres and the tibia about 41 centimetres, so the lower leg was slightly shorter than the thigh. This is not the same proportion seen in especially long-legged coelophysoids, and it cautions against copying their entire silhouette onto this genus.

The hind limbs support a bipedal stance. The forelimbs were substantially shorter, but the hand is incomplete and its exact grasping ability is not known. Serrated, recurved teeth indicate slicing bites consistent with a carnivorous diet. No sufficiently complete skull is available to calculate bite force, and comparisons with much later giant theropods would be speculative.

The bones cannot yield a reliable maximum running speed. Speed models need body mass, muscle cross-section, joint limits and stride lengths, several of which are uncertain here. Calling Liliensternus the “fastest Triassic predator” turns an unmeasured reconstruction into a record claim.

Environment and likely feeding

During the Norian, the type area lay within the Central European Basin. Red marls and mudstones accumulated on lowland plains with temporary water bodies, episodes of flooding and long dry intervals. The landscape was seasonal rather than a permanent tropical swamp. The Triassic Period included many different climates and habitats, so one German river plain should not stand for the entire supercontinent.

Large herbivorous sauropodomorphs and non-dinosaur reptiles shared the regional ecosystem. A predator the size of Liliensternus could have taken small vertebrates, juveniles or weakened animals, and scavenging is also possible. There are no stomach contents, coprolites or securely matched bite marks that identify a particular meal or prey species.

The bones of two animals in one collection do not show pack hunting. Sediment movement and accumulation can bring separate carcasses together. No nest, juvenile group, trackway or parental-care evidence is securely assigned to the genus. The better-supported ecological description is a bipedal carnivore in a diverse Late Triassic landscape, with its detailed behaviour still unknown.

The crest myth and other limits

Paired cranial crests are often added to Liliensternus, making its head resemble a smaller Dilophosaurus. The upper part of the skull is not preserved well enough to establish tall crests. Low bony ridges remain a possible reconstruction, but their height and shape are not direct observations. A bright display crest is an artistic choice rather than a documented feature.

The older combination Halticosaurus liliensterni explains why older references use a different genus name; it is not the current classification. Nor is Liliensternus a direct ancestor of tyrannosaurs. It represents one early neotheropod branch, and a branching relationship is not a ladder in which every older species becomes the ancestor of a later one.

Skin, feathers, colour, calls and social behaviour are unknown for this fossil collection. The surviving anatomy constrains a bipedal body and a carnivorous feeding apparatus more strongly than it constrains soft tissues or life history. Profiles in the dinosaur catalogue allow comparison with other early theropods without treating missing bones as if they had been found.