Ancient porcupine fossils reveal first island colonisation in Pleistocene Taiwan

Deep in the riverbed of the Tsailiao River in south-western Taiwan, palaeontologists have uncovered something remarkable: the fossilised teeth of a porcupine that somehow reached an island. The specimens, described in the Swiss Journal of Palaeontology, belong to Hystrix subcristata, an extinct porcupine species known only from mainland East and Southeast Asia until now. The discovery marks the first island record for the entire genus Hystrix, the Old World porcupines, and pushes the species’ known range further east than any previous find.

The fossils come from the Chochen–Tsailiao locality in Tainan, part of the Chiting Formation dated to the Middle Pleistocene, roughly 800,000 to 400,000 years ago. The collection includes a well-preserved upper molar, a lower last premolar, a fragmentary lower molar and three fragmentary incisors. These teeth were pulled from reworked deposits along the riverbed, mixed from both marine and terrestrial layers, which is why researchers adopt a conservative age range for the material.

Identifying porcupine species from teeth alone is notoriously tricky. The team relied on four key dental characters: overall size, occlusal outline, occlusal pattern and degree of hypsodonty, or enamel height. But as previous studies have shown, the occlusal morphology of Hystrix has remained remarkably conservative from the Miocene through to the present, and crown height barely differs between Pleistocene and living species. That leaves size as the most diagnostic criterion, and here the Taiwanese specimens tell a clear story.

Biometric analysis shows the Chochen–Tsailiao teeth are smaller than those of Hystrix refossa, a very large Plio–Pleistocene porcupine whose lower fourth premolar ranges from 10 to 13 millimetres in length, considerably bigger than the Taiwanese specimen at 9.2 millimetres. The fossils are also larger than Hystrix lagrelii, the smallest known Pleistocene porcupine, and Hystrix vinogradovi, a small European and West-Central Asian species. Instead, the measurements fall squarely within the range of Hystrix subcristata from Middle Pleistocene sites across China.

Morphological features back up the size evidence. The upper molar shows an anteriorly oval and posteriorly square outline with seven enamel islands and no enamel folds, indicating an adult individual. The lower fourth premolar, with its pyriform shape and four lingual synclines, belongs to a subadult. The heavily worn lower molar, with six enamel islands and connected lophids, comes from an old individual. Together, these details match the evolutionary state of H. subcristata populations and distinguish the material from smaller forms like H. lagrelii.

The taxonomic picture is complicated by ongoing debate. Some researchers have treated H. subcristata as a subspecies of the living Malayan porcupine Hystrix brachyura, while others regard it as a distinct species based on skull differences. A more recent proposal even suggested uniting all large Pleistocene porcupines from East and Southeast Asia under a single species, H. kiangsenensis. The team behind the new study follows the classification of H. subcristata as a distinct species, grounded in extensive comparative analyses of both fossil and living skulls. Genetic studies have added further layers of complexity, showing clear distinctions between ancient Tianyuan Cave porcupines and living species while simultaneously highlighting similarities with H. brachyura.

Geography helps rule out some alternatives. Hystrix cristata, the crested porcupine, overlaps in dental size with H. subcristata but is restricted to Africa and westernmost Eurasia, specifically Italy and France, making it palaeobiogeographically improbable that the Taiwanese fossils belong to this species. Hystrix vinogradovi, distributed across Europe and West-Central Asia, is likewise geographically distant. The closest comparable species, H. kiangsenensis from Lang Trang Cave in Vietnam, is similar in size but displays greater hypsodonty and a squarer lateral morphology in the Taiwanese specimen.

The discovery significantly broadens the palaeobiogeographical range of Hystrix. According to the NOW database, the fossil record of H. subcristata stretches from Zhoukoudian in northern China to Tham Wiman Nakin in Thailand, with the easternmost limit previously at Fenghuangshan, China. The geographically most proximal localities to Taiwan are in Fujian Province, China, including Yongan, Jiandaodun and Hulidong from the Middle Pleistocene. The faunal assemblages of Hulidong and Jiandaodun show notable taxonomic similarities to the Chochen–Tsailiao locality, hinting at Middle Pleistocene biogeographic connections between Taiwan and the mainland.

How porcupines reached Taiwan remains an open question. The Chiting Formation has yielded a rich vertebrate assemblage including primates, proboscideans, suids, cervids, rhinoceroses, crocodiles, snakes, a toad, a bird and fishes, suggesting a diverse ecosystem where terrestrial mammals thrived. Many fossils were reworked from mixed marine and terrestrial deposits, complicating precise dating but confirming a Middle Pleistocene age. Whether porcupines crossed land bridges during sea-level lowstands or arrived by other means, the new fossils provide the first concrete evidence for Quaternary mammal dispersal between continental East Asia and adjacent islands.

Future research will focus on quantitative faunal similarity analyses between the Taiwanese locality and mainland sites to clarify these ancient connections. For now, the Chochen–Tsailiao porcupine stands as a testament to the reach of Pleistocene mammals, extending the known distribution of H. subcristata eastwards and marking the first island record for a genus that has roamed Eurasia since the Late Neogene.

Subject of Research: Palaeontology

Article Title: First island colonisation by Hystrix subcristata ( Mammalia , Rodentia ): fossil evidence from Pleistocene, southern Taiwan

Article References: Halaçlar, K., & Lin, C.-H. (2026). First island colonisation by Hystrix subcristata (Mammalia, Rodentia): fossil evidence from Pleistocene, southern Taiwan. Swiss Journal of Palaeontology, 145, 293-302. https://doi.org/10.3897/sjp.145.175168

Image Credits: AI Generated

DOI: 10.3897/sjp.145.175168

Keywords: Hystrix subcristata, porcupine, Taiwan, Pleistocene, island biogeography, palaeontology, First, island, colonisation, Hystrix, subcristata, Mammalia