Scientists Identify Giant New Dinosaur Species from Fossils Discovered in Thailand

In 2016, a local resident named Thanom Luangnan spotted unusual shapes protruding from rock near a pond in Chaiyaphum Province, northeastern Thailand [1]. A decade later, those fragments have been formally described as Nagatitan chaiyaphumensis — a roughly 27-meter-long sauropod dinosaur and the largest ever found in Southeast Asia [2]. The study, published May 14, 2026 in Scientific Reports, positions the animal as a critical link in understanding how some dinosaur lineages ballooned to extraordinary sizes during the middle Cretaceous [3].

What Was Found — and What Wasn't

Between 2016 and 2019, excavation teams from Thailand's Department of Mineral Resources recovered 10 bones from the site, including vertebrae, ribs, hip bones, and limb elements [1]. The most striking specimen is a right humerus — the upper forelimb bone — measuring nearly 1.8 meters (about 6 feet), the largest dinosaur limb bone ever recovered in the region [2]. A complete left femur was also preserved [3].

Ten bones from a single individual constitute a partial skeleton. No skull material was recovered, and large sections of the vertebral column, tail, and forelimbs remain missing. Mathew Wedel, a paleontologist at the Western University of Health Sciences in Pomona, California, who was not involved in the study, offered a measured endorsement: "We've got several regions of skeleton represented...enough to give us a lot of information" [4]. Pedro Mocho of the Universidade de Lisboa added that the material was "substantially more complete" than previous Thai sauropod finds, which had consisted largely of isolated or fragmentary elements [5].

Still, the size and mass estimates — approximately 27 meters long and 25 to 28 metric tons — depend partly on scaling relationships derived from more complete specimens of related species [3]. This is standard practice in sauropod paleontology, where complete skeletons are rare, but it introduces uncertainty. No published criticism of the species diagnosis has appeared as of mid-May 2026, though the paper has been available for peer scrutiny for only days.

Classification: Why a New Species?

The research team, led by Thitiwoot "Perth" Sethapanichsakul, a Ph.D. student at University College London, classified Nagatitan within Euhelopodidae, a family of somphospondylan titanosauriforms — a group of sauropods characterized by elongated forelimbs and spongy internal bone structure [3]. The name combines "Naga," the mythological serpent of Southeast Asian tradition, with "titan," a reference to its size [2].

To arrive at the classification, the team conducted a phylogenetic analysis comparing Nagatitan against more than 150 other sauropod species [3]. Several anatomical features of the vertebrae and limb bones distinguished it from its closest known relatives. Because Euhelopodidae is known primarily from East Asian fossils, the placement reinforces a pattern of sauropod diversification across Cretaceous-era Asia [3][5].

Size in Context: Large, But Not the Largest

Nagatitan is the largest dinosaur found in Southeast Asia, but it is far from the largest sauropod globally. At an estimated 27 meters and 25–28 tonnes, it exceeds the famous Diplodocus (about 26 meters, ~14 tonnes) in both length and mass [6]. Lead author Sethapanichsakul noted that Nagatitan "likely weighed at least 10 tons more than Dippy the Diplodocus" [4].

However, the South American titanosaurs occupy a different scale entirely. Patagotitan mayorum, from Argentina, reached approximately 37 meters and an estimated 77 tonnes [7]. Argentinosaurus, also from Argentina, is estimated at 30–35 meters and 65–80 tonnes [8]. Dreadnoughtus, another Argentine giant, weighed roughly 50 tonnes [7]. Even within Asia, the Chinese Ruyangosaurus may have weighed 50–60 tonnes [6].

Source: Scientific literature compilation

Data as of May 15, 2026CSV

What makes Nagatitan scientifically significant is not its absolute size but its phylogenetic and temporal position. The researchers interpret it as representing an early stage of a broader body-size increase among Asian titanosauriforms during the middle Cretaceous — what the team described as "the on-ramp" toward the super-giants that emerged later in China, South America, and Africa [3][4].

Geological Age and What It Reveals

The fossils come from the Khok Kruat Formation, dated to approximately 113 million years ago — the Late Early Cretaceous (Aptian-Albian boundary) [3]. This is Thailand's youngest dinosaur-bearing rock formation. Overlying strata represent shallow marine environments, meaning the Khok Kruat Formation captures the final chapter of terrestrial dinosaur life in this part of Thailand before the region was submerged by rising seas [2][3].

The Aptian-Albian boundary is significant for global paleogeography. During this period, land bridges and island chains connected parts of Southeast Asia to the broader Asian continent and, more tenuously, to Gondwanan landmasses [9]. The presence of a euhelopodid sauropod in Thailand is consistent with faunal exchange across East and Southeast Asia, and the Khok Kruat Formation has also yielded iguanodontians, basal ceratopsians, carcharodontosaurian and spinosaurid theropods, sharks, turtles, crocodilians, and pterosaurs [3][5]. This diverse assemblage suggests robust land connectivity across the region during the Early Cretaceous.

The Ecosystem That Sustained a Giant

Mesozoic Southeast Asia was warmer and wetter than the present day, with an East Asian monsoon system already operating during the Early Cretaceous [9][10]. The vegetation would have included extensive cycad and conifer forests, with angiosperms (flowering plants) beginning their rapid radiation during this period [10]. These conditions could have supported large-bodied herbivores, though the specific vegetation density and food-web structures of the Khok Kruat ecosystem remain poorly understood compared to the well-studied Morrison Formation of North America or the Patagonian basins of Argentina.

The coexistence of Nagatitan with spinosaurid and carcharodontosaurian predators — both large-bodied theropod families — implies a food web with multiple trophic levels and sufficient primary productivity to sustain animals at the top of the size spectrum [3]. However, detailed paleoecological reconstruction of this specific formation awaits further fieldwork and analysis.

Thailand's Paleontological Track Record

Nagatitan is the 14th named dinosaur species from Thailand [2]. The country's fossil record dates to 1973, when uranium prospectors discovered bones in the Phu Wiang mountains of Khon Kaen Province [11]. Since 1976, a Thai-French collaborative project between Thailand's Department of Mineral Resources and French paleontological institutions has driven much of the fieldwork [11].

Sauropod remains dominate the Thai Mesozoic vertebrate record, and the country's dinosaur diversity ranks among the highest in Asia despite its relatively modest geographic area [11]. Key institutions include the Department of Mineral Resources (the primary government body for paleontological excavation), the Paleontology Research and Education Center at Mahasarakham University (founded in 2002), and the Phu Wiang Dinosaur Museum (opened in 2001) [11][12].

Funding, Access, and the Gap in Southeast Asian Paleontology

The Nagatitan project illustrates a recurring challenge. After the initial 2016–2019 excavation recovered 10 bones, funding dried up and work halted for approximately five years before resuming in 2024 [1][4]. This kind of interruption is common in Southeast Asian paleontology, where research budgets are small and institutional support for fieldwork is inconsistent.

Thailand enacted a fossil protection law in 2008, a turning point for the field [13]. Before the law, fossils were regularly smuggled onto the international black market, and local residents sometimes fashioned them into amulets [13]. The legislation enabled the government to allocate dedicated budgets for hiring experts, funding research, and building museums, and it codified fossils as national heritage [13].

The Nagatitan study exemplifies the international collaboration model that has driven Thai paleontology forward. The lead author, Sethapanichsakul, is a Thai national pursuing a doctorate at UCL, co-authoring with Sita Manitkoon of Mahasarakham University (who is also a National Geographic Explorer) and UCL's Paul Upchurch [3]. Portuguese researcher Pedro Mocho of the Universidade de Lisboa also contributed to the broader scholarly commentary [5].

Under Thai law, the fossils remain national property. The terms of international collaboration typically allow visiting researchers access for study while requiring that physical specimens stay in Thailand, usually housed at the Department of Mineral Resources or affiliated museums [11][13]. Casts and 3D scans facilitate access for researchers abroad.

The Broader Trend in Sauropod Research

Academic interest in sauropod dinosaurs has grown substantially over the past 15 years. According to OpenAlex data, annual peer-reviewed publications on "dinosaur sauropod" topics rose from 136 papers in 2011 to a peak of 349 in 2025, with 87 papers already published in the first months of 2026 [14].

Source: OpenAlex

Data as of Jan 1, 2026CSV

This surge reflects both new discoveries — from Argentina, China, and now Southeast Asia — and advances in analytical techniques, including CT scanning, histological analysis of bone microstructure, and computational phylogenetics. Finds like Nagatitan contribute to a richer global picture of how sauropods evolved, diversified, and achieved extreme body sizes across multiple continents and geological periods.

What Comes Next

Further excavation at the Chaiyaphum site could yield additional Nagatitan material, potentially resolving questions about the species' anatomy that the current 10-bone assemblage cannot answer. Sethapanichsakul has indicated that fieldwork is ongoing [4]. The Khok Kruat Formation, as the youngest dinosaur-bearing unit in the Thai stratigraphic sequence, may also preserve the last records of other dinosaur lineages in the region before marine transgression ended terrestrial fossil deposition [3].

For Southeast Asian paleontology more broadly, the discovery reinforces an argument that the region's fossil record remains significantly undersampled relative to its geological potential. With only a handful of professional paleontologists and limited excavation infrastructure compared to the well-funded programs of China, Argentina, and the United States, Thailand and its neighbors may harbor many more species awaiting discovery — if the resources to find them materialize.