New findings of Changxingaspis(Xiushuiaspidae,Galeaspida)from the Silurian of Tarim Basin and Zhejiang Province,China

New discovery of the early Silurian fossil fish Changxingaspis(Xiushuiaspidae,Galeaspida),Changxingaspis nianzhongi sp.nov.and C.gui,are described from the Tataertag Formation in Tarim Basin and the Kangshan Formation in Zhejiang Province,respectively.C.nianzhongi mainly differs from C.gui in the shape of the median dorsal opening that is transverse elliptic with a width/length ratio of about 3.0,the long lateral transverse canals extending to the lateral margin of the headshield,and the second lateral transverse canal with dichotomous branchings.Discovery of C.nianzhongi from the Tataertag Formation and C.gui from the Kangshan Formation provide direct evidence on the specific level for the correlation between these two formations,which further supports the Silurian fish-bearing red beds in northwest Zhejiang belonging to the Silurian Lower Red Beds(LRBs)rather than the Upper Red Beds(URBs).Additionally,as the first record of the Changxingaspis in Tarim Basin,it extends the paleogeographical distribution of this genus from the South China Block to the Tarim Block,providing new evidence to support faunal exchanges between these two blocks and the hypothesis of a united Tarim-South China Block during the early Silurian.

A New Triassic Primitive Ichthyosaur from Yuanan, South China

Based on the systematic study of two fossil skeleton specimens collected from the top of the third member of the marine Lower Triassic Jialingjiang Formation of Yuanan, Hubei Province, South China, a new Early Triassic primitive ichthyosaur Chaohusaurus zhang]iawanensis sp. nov. is reported and described. The beds yielding the type material are correlated with the Neospathodus homeri-N, triangularis Conodont zone. The new taxon is most similar to Chaohusaurus geishanensis Young and Dong, 1972 in the shape and configuration of the scapula, forefin, pelvic girdle and hindfin, presacral vertebral count and well-developed caudal peak, but distinguished from the latter by its larger size, the position of the pineal foramen in the centre of the parietal, the occurrence of a larger calcaneum in hindfin and the first sacral rib with distal expansion. The new species exhibits common features of primitive ichthyosaurs such as： （1） the prefrontal has an antero-dorsal shelf projecting towards the orbit; （2） the upper temporal fenestra is small; （3） the postorbital and the squamosal meet laterally to the upper temporal fenestra; and （4） cylindrical centra. However, more derived ichthyosaur characters are seen with the frontal separated from the orbital dorsal margin by the contact of the prefrontal and postfrontal, which offer new clues to the early radiation of ichthyosaurs.

A New Family of Galeaspids(Jawless Stem-Gnathostomata) from the Early Silurian of Chongqing, Southwestern China

A new genus and species of agnathan Eugaleaspidiformes(Galeaspida), Yongdongaspis littoralis gen. et sp. nov., is described from the Llandovery(lower Silurian) Huixingshao Formation at Yongdong Town, Xiushan County, Chongqing, southwestern China. This new Telychian taxon morphologically exhibits some transitional states between Sinogaleaspidae and a cluster of higher eugaleaspidiforms containing Tridensaspidae, Eugaleaspidae, Yunnanogaleaspis, and Nochelaspis, which we term here as the ’eugaleaspid cluster’. Phylogenetic analysis of an extended character matrix of Galeaspida reveals Yongdongaspis, on which Yongdongaspidae fam. nov. is erected, as the sister taxon of this ’eugaleaspid cluster’, supported by two synapomorphies, the presence of one median transverse canal, and two lateral transverse canals leaving from the infraorbital canal. As the first fish described from the Llandovery Huixingshao Formation in Chongqing, Yongdongaspis provides new fossil evidence for the subdivision and correlation of the Upper Red Beds in South China.

Discovery of a New Middle Jurassic Dinosaur Site in Sichuan,China

The Sichuan Basin,also known as the‘Red Basin’,is famous for its abundance of Mesozoic dinosaur fossils,especially in the Zigong area during the Jurassic era;the Middle Jurassic Shunosaurus and the Late Jurassic Mamenchisaurus faunal assemblages are the most representative.The Qinglongshan dinosaur fossil site is located in Fuxing,to the northwest of Rong County,Zigong City.This new site is situated within the Middle Jurassic Xiashaximiao Formation,and geologically is roughly equivalent to the well-known Dashanpu dinosaur fossil site.More than 600 dinosaur fossils were found concentrated in the excavation area,including teeth;cervical,dorsal and caudal vertebrae;and various parts of appendicular skeletons.This fossil site is also most significant as it provides new information on non-avian dinosaur life during the poorly understood Middle Jurassic.

Strenulagus(Mammalia: Lagomorpha) from the Middle Eocene Irdin Manha Formation of the Erlian Basin, Nei Mongol, China

New material of Strenulagus solaris, a stem lagomorph, from the lower part of the Middle Eocene Irdin Manha Formation at the Irdin Manha and Huheboerhe localities, Erlian Basin, Nei Mongol, China includes remains of isolated cheek teeth, fragmentary upper incisors （dI2） and postcranial elements, reported from the species for the first time. The tarsal bones display advanced features, such as a wide calcaneofibular articulation surface and, along with an increase in hypsodonty, the new data document the early stage of lagomorph evolution in the Middle Eocene of the Erlian Basin. This finding is stratigraphically well constrained and probably predates that of the type material of S. solaris from the Khaychin Formation, Bugin-Tsav Basin, Mongolia.

Oldest Asian Record of Snapping Shrimps(Malacostraca:Alpheidae)from the Kutch Basin,Western India and Associated Biota:Biostratigraphic,Paleoenvironmental and Paleoecological Significance

The oldest Asian record of alpheid shrimps,assigned to genus Alpheus,based on snapping claw fingertips from the Miocene Khari Nadi Formation in the Kutch Basin,western India reported herein,extends the fossil record of the family Alpheidae from Asia by~22 million years.An early Miocene(Aquitanian)age is estimated based on the associated assemblage of calcareous nannofossils,Sphenolithus disbelemnos,Cyclicargolithus floridanus,and Reticulofenestra haqii.The co-occurring microbiota includes bony fish otolith remains,identified as“genus Gobiidarum”,isolated teeth of Dasyatis rays,Sphyrna sharks,and teleosts,ctenoid and placoid scales,ostracods,belonging to the genera Paractinocythereis,Alocopocythere,Ruggieria,Aglaiocypris,Bairdoppilata,and echinoid spines.Taken together,the microfossil assemblage and data from chemical analyses using Energy Dispersive Spectroscopy,X-Ray Diffraction and Wavelength Dispersive X-Ray Fluorescence of host and associated lithologies suggests prevalence of a shallow(neritic)to coastal marine(intertidal)depositional paleoenvironment.The present investigation also provides the oldest fossil evidence on the co-occurrence of Alpheus and gobiids(based on otoliths)that strongly advocates that the mutualistic association between these animal groups had developed by the Aquitanian.

First Record of Petalodus Owen,1840(Chondrichthyes,Petalodontidae)in the Lower Permian(Cisuralian)of China

The Petalodontiformes are a small intriguing group of Permo–Carboniferous chondrichthyans.Petalodus is the longest known petalodont genus generally considered representative of the order.The first definite fossil record of seven well-preserved Petalodus teeth has been found in the Qianshi limestone in the Lower Permian(Cisuralian)middle–upper Taiyuan Formation in Yangquan City,Shanxi Province,North China.The specimens are characterized by petal-shaped teeth with a spade-like crown,and a long,tongue-shaped root;the crown is circled with a band or cingulum composed of imbricated ridges at the base.All seven teeth are assigned to the species P.ohioenesis because of their vertically narrow cingulum and much longer root.Petalodus is a worldwide genus,with fossil localities mainly concentrated in the Laurussia supercontinent.The occurrence of Petalodus teeth in Yangquan not only is the first fossil record in China,but also only the second record in Asia.The Yangquan fossil site was part of the paleoequatorial North China Craton during the Early Permian,and was isolated from Laurusia and East Gondwana by the Paleo-Tethys Ocean.The successful dispersal of Petalodus from Laurusia to the North China Block along Paleo-Tethys may support the possibility that Petalodus taxa were active free-swimmers rather than bottom dwellers.The new finding increases the petalodont diversity in eastern Asia,and also sheds new light on the distribution and stratigraphic range.

Tooth Plates of Ceratodus(Dipnoi,Ceratodontidae)from the Upper Jurassic Shaximiao Formation of Guang’an,Sichuan Province,China

Ceratodus is a form genus of ceratodontid lungfishes.Until now,only 14 specimens have been reported from the Mesozoic of China.Detailed measurements and characteristic comparisons based on 15 well-preserved lungfish tooth plates of Ceratodus type,uncovered from the upper member of the Upper Jurassic Shaximiao Formation at Luojiashan,Qianfeng District,Guang'an,Sichuan Province in 2019,allow us to establish a new species,Ceratodus guanganensis sp.nov.,on the basis of its small swollen irregular triangular tooth plate with four low and swollen radial crests on the occlusal surface without denticles.Other specimens from the same locality can be referred to C.szechuanensis and C.youngi.This is the first discovery of Ceratodus in the Guang'an region and represents the fifth Ceratodus fossil site in the Sichuan Basin.The discovery indicates that the climate was hot and arid in the Sichuan Basin during the Late Jurassic,and reveals a tectonic paleogeographic relationship between the Yangtze block in southwestern China and the Kola Basin in northern Thailand.

New Discovery of Hipparion theobaldi Skull from the Late Miocene of Padhri,District Jhelum,Punjab,Pakistan and Associated Mammalian Fossil Assemblage

A fossil-bearing locality near Padhri village,Dhok Pathan,55 km away from the tehsil Dina,Jhelum District,in the Potwar Plateau,Middle Siwaliks,Punjab,northern Pakistan,is significantly rich in mammalian fossils.This site has provided an abundant mammalian fossil fauna of Late Miocene age from the Dhok Pathan Formation(Fm.).The recovered material belongs to four families:Equidae(horses),Rhinocerotidae(rhinos),Bovidae(cows),and Suidae(pigs).We discovered a new skull of hipparionine Hipparion theobaldi from this locality along with 22 specimens from the associated assemblage of fossil mammals.The recovered material includes seven other species:the aceratheriine Chilotherium intermedium,boselaphines Tragoportax punjabicus,Selenoportax vexillarius,Pachyportax latidens,the antelope Gazella lydekkeri and suinine Propotamochoerus hysudricus.The specimens are isolated teeth,fragments of maxilla,mandibles and horn cores.The Dhok Pathan Fm.is generally composed of claystone,siltstone and sandstone beds and,based on the mammalian fauna,the Padhri fossil locality is dated as Late Miocene.Thi99 s formation was deposited in a subtropical paleoenvironment and the predominance of fossil bovids indicates extremely moist conditions with small but frequent standing water bodies.