The Nanxiong Formation (also known as Yuanpu Formation) is a Late Cretaceous geologic formation in Jiangxi and Guangdong Provinces. Dinosaur remains are among the fossils that have been recovered from the formation.
Description It consists of continental siliciclastic red beds, with fauna which similar to that of the Nemegt Formation. It has been dated to about 66.7 ± 0.3 million years ago. It is the lowest unit of the Nanxiong Basin, a small graben created during Mesozoic rifting. Buck et al. state that it overlies Jurassic granite basement, and is conformably overlain by the Shanghu Formation. Alternative stratigraphic schemes for the Nanxiong basin have been proposed, one of which refers to the Nanxiong succession as the Nanxiong Group, and dividing it into the Yuanpu, Zhutian and Zhenshui formations, and overlying the Albian to Turonian Changba Formation. The age of the Nanxiong basin as a whole has been constrained to 72 to 62.8 mya.
The depositional environment is made up of alluvial fan facies consisting of sheetflood deposits and ephemeral braided rivers. Adjacent to these are ephemeral saline playa facies recording features such as root traces, desiccation cracks, and calcareous paleosols. In situ desert varnish and minor paleosol development on alluvial facies due to inactivity are indicative of arid conditions. Stable carbon and oxygen isotopes from Dinosaur eggshells were used to estimate a mean annual temperature between , with positive isotope perturbations around the K/Pg boundary indicating periods where temperatures may have exceeded .
Subsequent research has reinterpreted many of the vertebrate fossils from the Nanxiong Formation as instead coming from the Hekou Formation, with the "Nanxiong Formation" instead equivalent to the Guifeng Group.
Fossil content
Dinosaurs
Ornithischians Ornithischians of the Nanxiong FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImage Microhadrosaurus M. nanshiungensis Guangdong Province, China Maastrichtian Partial lower jaw from a juvenile that was about 2.6 m long. A dubious hadrosaurid hadrosaur Nodosauridae Indet. Indeterminate Guangdong and Jiangxi Provinces, China Maastrichtian Osteoderms. A nodosaurid ankylosaur
Sauropods Sauropods of the Nanxiong FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImage Gannansaurus G. sinensis Jiangxi Province, China Maastrichtian A single, nearly complete dorsal vertebra and a mid-caudal vertebra. A euhelopodid somphospondylian; closely related to Euhelopus zdanskyi. Jiangxititan J. ganzhouensis Jiangxi Province, China Maastrichtian The three posteriormost cervical vertebrae with two cervical ribs, articulated with the first four dorsal vertebrae with three dorsal ribs. A somphospondylian sauropod
Theropods Theropods of the Nanxiong FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImage Asiatyrannus A. xui Jiangxi Province, China Maastrichtian A skull, partial legs, and fragmentary caudal vertebrae. A small-bodied tyrannosaurine tyrannosaurid; suggested by some researchers to be a possible juvenile Tarbosaurus bataar. Banji B. long Jiangxi Province, China Maastrichtian Nearly complete skull and lower jaw. A oviraptorid oviraptorisaur Corythoraptor C. jacobsi Jiangxi Province, China Maastrichtian Nearly complete skeleton including the skull and lower jaw. A oviraptorine oviraptorid; with a distinct cassowary-like crest. Ganzhousaurus G. nankangensis Jiangxi Province, China Maastrichtian Lower jaw, leg bone, hip bone and caudal vertebrae. A heyuanniine oviraptorid Huanansaurus H. ganzhouensis Jiangxi Province, China Campanian to Maastrichtian Nearly complete skull, lower jaws, neck vertebrae, a humerus, arm fragments, lower part of the right thighbone, the upper part of the right shinbone, and parts of the right foot. A oviraptorine oviraptorid Jiangxisaurus J. ganzhouensis Jiangxi Province, China Maastrichtian Incomplete skull, lower jaw, vertebrae, nearly complete pectoral girdle, the left forelimb, ribs, and a partially preserved pelvic girdle. A heyuanniine oviraptorid Nankangia N. jiangxiensis Jiangxi Province, China Maastrichtian A partial lower jaw, vertebrae, both scapulocoracoids, a nearly complete right humerus, pubic bones, and some dorsal ribs. A caenagnathoid oviraptorosaur Nanshiungosaurus Translated paper (Archived from original) N. brevispinus Guangdong Province, China Maastrichtian Eleven cervical vertebrae, ten dorsal vertebrae, six sacral vertebrae and the pelvis. A therizinosaurid therizinosauroid Oviraptoridae Indet. Indeterminate Jiangxi Province, China Maastrichtian A female individual preserving a partial pelvic girdle, hindlimbs and some caudals with two eggs associated near the pelvic region. A oviraptorid oviraptoosaur Indeterminate Guangdong Province, China Maastrichtian A nesting adult over a nest of eggs, preserving cervical vertebrae, arms and the pelvic region. A oviraptorid oviraptorosaur; that represents the fifth nesting taxon. Indeterminate Jiangxi Province, China Maastrichtian A female individual preserving a partial pelvic girdle, hindlimbs and some caudals with two eggs associated near the pelvic region. A oviraptorid oviraptorosaur Qianzhousaurus Q. sinensis Jiangxi Province, China Maastrichtian A skull, lower jaw, vertebrae, both scapulocoracoids, a left femur and a left tibia. A alioramin tyrannosaurine; closely relate to Alioramus altai. Shixinggia S. oblita Guangdong Province, China Maastrichtian Sparse postcranial remains lacking the skull. A oviraptorid oviraptorosaur; the pose indicates that it may have died trying to free itself from mud. Theropoda Indet. Indeterminate Jiangxi Province, China Maastrichtian A maxillary tooth that differs from tyrannosaurid and carcharodontosaurid dentition. A notably large theropod Indeterminate Guangdong Province, China Maastrichtian Isolated dorsal vertebra. An indeterminate theropod. Tongtianlong T. limosus Jiangxi Province, China Maastrichtian Almost complete skeleton, portions of the arms, right leg, and tail were destroyed by TNT blasts. A oviraptorid oviraptorosaur Tyrannosauridae indet. Indeterminate Guangdong Province, China Maastrichtian Two isolated teeth. A tyrannosaurid tyrannosauroid Indeterminate Jiangxi Province, China Maastrichtian Large and well-preserved tooth. A tyrannosaurid tyrannosauroid
Crocodilians Crocodilians of the Nanxiong FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImage Jiangxisuchus J. nankangensis Jiangxi Province, China Maastrichtian Nearly complete skull and mandible. A orientalosuchine alligatoroid
Squamates Squamates of the Nanxiong FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImage Chianghsia C. nankangensis Jiangxi Province, China Maastrichtian A partial skull and lower jaws. A monstersaurian lizard Tianyusaurus T. zhengi Jiangxi Province, China Maastrichtian A skull, mandible, first eight cervical vertebrae and nearly complete pectoral girdles. A polyglyphanodontian lizard; also known from the Qiupa Formation.
Turtles Turtles of the Nanxiong FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImage Jiangxichelys J. ganzhouensis Jiangxi Province, China Maastrichtian A complete shell. A nanhsiungchelyid turtle Nanhsiungchelys N. wuchingensis Guangdong Province, China Maastrichtian A partial skeleton. A nanhsiungchelyid turtle
Ichnofossils Ichnofossils of the Nanxiong FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImage Hadrosauropodus isp. Indeterminate Guangdong and Jiangxi Provinces, China Maastrichtian Three-toed footprints. A hadrosaur
Oofossils Oofossils of the Nanxiong FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImage Elongatoolithidae indet. Indeterminate Jiangxi and Guangdong Provinces Maastrichtian Three eggs with embryonic remains. Oviraptorid eggs Macroolithus Indeterminate Jiangxi Province, China Maastrichtian Five egg clutches containing over 60 eggs. Oviraptorid eggs Indeterminate Guangdong Province, China Maastrichtian Three eggs with embryonic remains. Oviraptorid eggs M. yaotunensis Jiangxi Province, China Maastrichtian Two eggs with embryonic remains. Oviraptorid eggs. Skeletal proportions resemble Heyuannia huangi. M. yaotunensis Guangdong Province, China Maastrichtian A nest of 24 eggs associated with an adult oviraptorid. Oviraptorid eggs Oolithes O. elongatus Jiangxi Province, China Maastrichtian Egg and egg clutches. Some of these were probably laid by Nanhsiungchelys wuchingensis. Turtle and/or theropod eggs. O. nanhsiungensis O. rugustus O. spheroides
See also List of dinosaur-bearing rock formations Dalangshan Formation
References