Qinglongtriton gangouensis is a Late Jurassic salamander from the Tiaojishan Formation of Hebei, China. The holotype and additional fossils include juveniles and adults, allowing researchers to compare growth rather than relying on one isolated skull. CT imaging reveals details hidden inside the bones, while the adult anatomy retains aquatic traits. The species is among the well-documented salamanders in the ancient amphibian catalogue.
Quick facts
| Species | Qinglongtriton gangouensis |
|---|---|
| Group | Caudata; Jurassic salamander |
| Age | Oxfordian, Late Jurassic |
| Formation | Tiaojishan Formation |
| Locality | Nanshimenzi, Qinglong County, Hebei, China |
| Holotype | PKUP V0226, skull about 45.11 mm long |
| In the catalogue | Ancient amphibians |
What the fossils establish
The type skull measures about 45 millimetres. A growth series shows that the angular bone progressively fuses with the prearticular in larger individuals.
These radiometric dates constrain the interval of the formation, not the death date of each specimen.
The stapes, palate and lower jaw preserve characters used in comparisons. CT imaging makes hidden structures visible but does not remove uncertainty in evolutionary interpretation.
A broader 2022 analysis placed several Jurassic taxa along the salamander stem. These are competing phylogenetic results, not disagreement about the fossils themselves.
A salamander series from northern China
Jia Jia and Gao Ke-Qin named Qinglongtriton gangouensis in 2016 from fossils at Nanshimenzi in Qinglong County, Hebei Province. The remains come from the Tiaojishan Formation, a sequence of volcanic and sedimentary rocks that preserves a rich Jurassic biota. The holotype is PKUP V0226, with a skull about 45.11 millimetres long.
Unlike many fossil salamanders known from a single vertebra or jaw, the collection contains a substantial sample of different sizes. The original study described 46 juvenile and adult specimens. Not every specimen preserves the same anatomy, but the series allows researchers to distinguish growth changes from differences that might indicate separate species.
Radiometric dates from volcanic beds in the region fall around 160.9 to 160.3 million years ago. These measurements constrain the age of the rock sequence. They should not be interpreted as the exact age of an individual salamander fossil or as a date taken directly from its bones.
Growth and hidden anatomy
Computed tomography revealed internal parts of the skull that are difficult to inspect from the surface. The orbitosphenoid remained cartilaginous in even the larger specimens described, while the stapes retained a foramen absent in living salamanders. The lower jaw includes a toothed coronoid element, and its bones show a visible pattern of age-related fusion.
In smaller individuals, a boundary between the angular and prearticular is more apparent. In larger specimens, these bones become increasingly fused. This is a direct observation across the sample and cautions against treating every difference in a small fossil as a species-level distinction. A growth series can reveal how one animal changed as it matured.
The fossils are consistent with aquatic adults that retained features often associated with larval development, a condition called neoteny. The original authors interpreted the branchial apparatus and degree of ossification in this context. The presence and exact outline of soft external gills are not preserved as ordinary bone anatomy; an illustration of them is a reconstruction based on the skeletal evidence and comparison with living salamanders.
Position among early salamanders
The original phylogenetic analysis placed Qinglongtriton near Beiyanerpeton at the base of Salamandroidea. A broader 2022 analysis recovered several Jurassic salamanders along the stem lineage of living salamanders. The difference reflects taxon sampling and the characters included in each analysis. It does not mean the fossil identity or its measured bones changed.
Comparisons with Marmorerpeton help separate shared early salamander traits from aquatic specializations. The much younger Mioproteus belongs to a different branch and provides a later point of comparison. These relationships are hypotheses about evolutionary branching, not a ladder in which one named fossil must have turned directly into the next.
Lake life and its limits
The locality represents a lake environment, and the anatomy supports a water-associated life history. Small aquatic invertebrates are plausible prey, but no stomach contents establish a menu. The fossils also do not preserve exact swimming movements, mating behaviour or seasonal activity.
The strongest evidence is unusually informative: a type specimen, many additional individuals, internal anatomy visible through CT, and a range of growth stages. These observations document anatomy and development. Exact phylogenetic placement, soft gill form and details of behaviour remain interpretive.
Frequently asked questions
When did Qinglongtriton live?
It lived during the Oxfordian Age of the Late Jurassic, around 161–160 million years ago.
Where is the holotype?
PKUP V0226 is held in the palaeontological collection of Peking University.
What does the growth series show?
It records progressive fusion of lower-jaw bones and helps separate age-related changes from taxonomic differences.
Why do studies place it differently?
Phylogenetic analyses use different taxa and anatomical characters; the 2016 and 2022 analyses therefore frame its position differently.