Uragasaurus kalasinensis

Uragasaurus kalasinensis is an early-diverging mamenchisaurid identified from a single anterior dorsal vertebra from northeastern Thailand. The bone's external ridges, deep pneumatic recesses and honeycomb-like internal structure provide a diagnostic combination even though the rest of the animal is unknown. Phylogenetic analyses place it among the long-necked Asian mamenchisaurids and extend the family's named record into Thailand. Other sauropod bones occur at Phu Noi, but the describing authors did not refer them to Uragasaurus because they were not found in direct association with the holotype.

Its fossils occur between approximately 150 and 145.2 million years ago. Values shown here are approximate and reflect the current curated seed dataset.

Holotype PRC 460 is a compressed but well-preserved anterior dorsal vertebra. A Y-shaped arrangement of vertebral laminae, prominent teardrop-shaped pneumatic fossae and a subtriangular pleurocoel distinguish it from close relatives. CT slices reveal extensive camellate, or small-chambered, internal pneumaticity. No skull, neck, limbs, tail or body outline can presently be assigned to the species.

• Anterior dorsal vertebra with a diagnostic Y-shaped lamina pattern
• Prominent teardrop-shaped pneumatic fossae
• Subtriangular pleurocoel on the side of the centrum
• Camellate internal air chambers documented by CT scanning
• Early-diverging mamenchisaurid character combination

The holotype was recovered at Phu Noi near Ban Din Chi in Kham Muang District, Kalasin Province, from the lower Phu Kradung Formation. Apirut Nilpanapan, Sita Manitkoon, Varavudh Suteethorn and Komsorn Lauprasert named it in July 2026. The specimen is curated at Mahasarakham University's Palaeontological Research and Education Centre. Uraga is Sanskrit for serpent, alluding to the long neck typical of mamenchisaurids, while kalasinensis honours Kalasin Province.

Naming authors: Apirut Nilpanapan, Sita Manitkoon, Varavudh Suteethorn, Komsorn Lauprasert.

The lower Phu Kradung Formation records rivers, floodplains and palaeochannels in a continental basin. Sandstone, siltstone and mudstone at Phu Noi have also yielded fishes, lungfish, turtles, crocodile-line reptiles and small ornithischian dinosaurs. The broad latest-Jurassic age is better supported than a precise stage assignment.

Herbivory, four-legged locomotion and a long neck are inferred from its mamenchisaurid relationships, not preserved directly in the holotype. A herd shown in the life reconstruction is illustrative; no trackway, bonebed or associated individuals demonstrate grouping in Uragasaurus.

• It is the first mamenchisaurid dinosaur formally named from Thailand.
• CT scans reveal a honeycomb of air spaces inside the only known vertebra.
• The scientific name combines a Sanskrit word for serpent with Greek sauros, lizard.
• DinoTree deliberately leaves its length and mass blank because no defensible species-level estimate has been published.

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1. 01
   A new mamenchisaurid sauropod from the latest Jurassic of northeastern Thailand

   Apirut Nilpanapan, Sita Manitkoon, Varavudh Suteethorn, Komsorn Lauprasert · Scientific Reports 16 · 2026

   Open source
2. 02
   Palaeontological Research and Education Centre

   Mahasarakham University

   Open source