 |
| Minimocursor phunoiensis Manitkoon, Deesri, Khalloufi, Nonsrirach, Suteethorn, Chanthasit, Boonla & Buffetaut, 2023 มินิโมเคอร์เซอร์ ภูน้อยเอนซิส || DOI: 10.3390/d15070851 Drawings by Wongwech Chowchuvech and Sita Manitkoon. |
Abstract
An exceptional articulated skeleton of a new basal neornithischian dinosaur, Minimocursor phunoiensis gen. et sp. nov., was discovered in the Late Jurassic Phu Kradung Formation at the Phu Noi locality, Kalasin Province, Thailand, a highly productive non-marine fossil vertebrate locality of the Khorat Plateau. It is one of the best-preserved dinosaurs ever found in Southeast Asia. Minimocursor phunoiensis gen. et sp. nov. shows a combination of both plesiomorphic and apomorphic characters resembling those of Late Jurassic to Early Cretaceous small-bodied ornithischians from China: a low subtriangular boss is projected laterally on the surface of the jugal, the brevis shelf of the ilium is visible in lateral view along its entire length, a distinct supraacetabular flange is present on the pubic peduncle of the ilium, the prepubis tip extends beyond the distal end of the preacetabular process of the ilium, and the manus digit formula is ?-3-4-3-2. The phylogenetic analysis shows that this dinosaur is among the most basal neornithischians. This study provides a better understanding of the early evolution and taxonomic diversity of ornithischians in Southeast Asia.
Keywords: ornithischia; Southeast Asia; Khorat Plateau; Late Jurassic; Minimocursor phunoiensis
 |
| Skull of Minimocursor phunoiensis gen. et sp. nov. based on PRC 150 in left lateral view. Outline reconstruction of the skull (A); outline reconstruction of the skull with photos of the jugal (reversed), surangular, and angular (B); right jugal (C); and left surangular and angular (D). Scale bars: 1 cm. |
 |
| Left dentary (PRC 149) referred to Minimocursor phunoiensis gen. et sp. nov. from Phu Noi locality in labial (A), dorsal (B), and lingual views (C). Dentary teeth in labial (D) and lingual (E) views. |
 |
| Holotype of Minimocursor phunoiensis gen. et sp. nov., PRC 150, in left lateral view. Photograph (A) and interpretative drawing (B). |
 |
| Reconstruction of Minimocursor phunoiensis gen. et sp. nov. (PRC 150) in left lateral view (except reversed images of the right jugal). Recovered elements of the holotype shown in white (A); holotype with referred materials, which are not to scale, shown in light purple (B); and life restoration (C). Drawings by Wongwech Chowchuvech (A, B) and Sita Manitkoon (B). |
Systematic Palaeontology
Dinosauria Owen, 1842
Ornithischia Seeley, 1888
Neornithischia Cooper, 1985
Minimocursor gen. nov.
Minimocursor phunoiensis gen. et sp. nov.
Diagnosis. Ornithischian dinosaur distinguished by a unique combination of plesiomorphic and apomorphic characters resembling those of basal neornithischians: jugal posterior process bifurcated distally (present in Lesothosaurus, Jeholosaurus, Psittacosaurus, and some early thyreophorans including Emausaurus and Scelidosaurus); a low flattened subtriangular boss projects laterally on the surface of the jugal (report in Changchunsaurus, and some early ornithischians including Manidens and Lioceratops); the pre-caudal axial skeleton is composed of 15 dorsals and 5 sacrals (presente in Lesothosaurus, Agilisaurus and Hexinlusaurus); the brevis shelf of the ilium is visible in lateral view along its entire length (present in Agilisaurus, Sanxiasaurus and Lesothosaurus); a distinct supraacetabular flange is present on the pubic peduncle of the ilium (present in Agilisaurus, Sanxiasaurus, and some early thyreophorans including Scutellosaurus and Scelidosaurus).
Type locality and horizon. Phu Noi locality (a small hill as the Thai name indicates), Ban Din Chi Sub-district, Kham Muang District, Kalasin Province, Thailand; Upper Jurassic Phu Kradung Formation, Khorat Group. This locality is part of the Kalasin Geopark area.
Etymology. The generic name is from the Latin ‘minimus’, ‘the smallest’, referring to the holotype individual, which is smaller than any other neornithischians from the site, combined with the suffix ‘-cursor’, the Latin word for runner. The specific epithet is derived from the excavation site, Phu Noi.
 |
| Articulated dorsal vertebrae of Minimocursor phunoiensis gen. et sp. nov., PRC 150, with close-up on the ossified tendons, under UV light. |
 |
| Locality map and stratigraphy of Phu Noi locality, which has yielded the holotype of Minimocursor phunoiensis gen. et sp. nov. Map of Thailand, showing the location of Bangkok and Kalasin Province (A); map of Khorat Plateau, showing the distribution of the Lower Phu Kradung Formation and the location of Phu Noi locality (red star) (B); stratigraphic column of Phu Noi (modified from [26]) (C); photograph of the excavation site in 2023 (D). |
 |
| Palaeoenvironmental interpretation of the Late Jurassic Phu Kradung Formation of northeastern Thailand, including hybodont indet. with egg capsules (A), Acrodus kalasinensis (B), ptycholepid indet. (C), Isanichthys lertboosi (D), Ferganoceratodus annekempae (E), brachyopid indet. (F), Phunoichelys thirakupti (G), Kalasinemys prasarttongosothi (H), Indosinosuchus potamosiamensis (I), mamenchisaurid indet. (J), metriacanthosaurid indet. (K), stegosaur indet. (L), Minimocursor phunoiensis (M), and rhamphorhynchoid indet. (N). Drawing by Sakka Weerataweemat. |
Conclusions
The Phu Noi locality contains a wealth of specimens and has yielded an exceptionally articulated skeleton, which represents one of the best-preserved dinosaurs ever found in Southeast Asia. This is the earliest record of neornithischians in Southeast Asia, and the first dinosaur taxon named from the Phu Kradung Formation of Thailand. This finding increases diversity and helps to elucidate the evolution of basal neornithischian dinosaurs in this region. Many of the remaining bones are still under preparation, including another skull. These unpublished specimens may provide a better understanding of the biology of Minimocursor phunoiensis gen. et sp. nov. in the future.
This study also provides new palaeontological data to illustrate the palaeoecosystem to the general public, as well as improving the academic value of the Kalasin Geopark.
Sita Manitkoon, Uthumporn Deesri, Bouziane Khalloufi, Thanit Nonsrirach, Varavudh Suteethorn, Phornphen Chanthasit,Wansiri Boonla and Eric Buffetaut. 2023. A New Basal Neornithischian Dinosaur from the Phu Kradung Formation (Upper Jurassic) of Northeastern Thailand. Diversity. 15(7), 851. DOI: 10.3390/d15070851
facebook.com/PaleoToon/posts/787863516672516
(This article belongs to the Collection Feature Papers in Phylogeny and Evolution)
