Nicholas C. Fraser

How Time Flies for Flies: Diverse Diptera from the Triassic of Virginia and Early Radiation of the Order

Abstract The most diverse and best-preserved early fauna of flies (order Diptera) is described from the Late Carnian (Late Triassic, ca. 220 Ma) of Virginia, USA. Complete flies are preserved as aluminosilicate films on very fine-grained shales from the Cow Branch Formation, which is part of the Newark Supergroup of Early Mesozoic rift basins from eastern North America. The dipteran fauna consists of eight families (one new), 11 genera (five new), and 16 species (11 new), and includes the following taxa (Blagoderov and Grimaldi are the authors of all new names): Architipula youngi Krzemiński, Metarchilimonia krzeminskorum n.gen., n.sp., and M. solita n.sp. (Limoniidae); Triassopsychoda olseni n.gen., n.sp. (Psychodidae); Culicomorpha indet.; Yalea argentata (Krzemiński), Y. rectimedia n.sp., Alinka cara Krzemiński (Procramptonomyiidae); Veriplecia rugosa n.sp., Virginiptera certa n.gen., n.sp., V. similis n.sp., V. lativentra n.sp. (Paraxymyiidae); Brachyrhyphus distortus n.gen. n.sp. (Protorhyphidae); ?Crosaphis virginiensis n.sp. (Crosaphididae); and Prosechamyia trimedia n.gen., n.sp., P. dimedia n.sp. (Prosechamyiidae, new family). Particularly significant is a culicomorphan with a long proboscis, which is the earliest fossil record of a structure specialized apparently for blood feeding. Also, Prosechamyia appears to be a stem group to the very diverse infraorder Brachycera, the earliest definitive members of which appear in the Early Jurassic. Phylogenetic relationships of major clades of living and extinct nematocerous Diptera are analyzed, indicating that infraordinal-level diversification was complete by the Late Triassic. Flies did not reach modern levels of ecological abundance until the mid-Jurassic, apparently due to diversification within most infraorders by that time.

Basal dinosauriform remains from Britain and the diagnosis of the Dinosauria

A new genus and species of dinosauriform is described from the Triassic of south-west England. The description is based on isolated elements recovered from an assemblage of other dissociated tetrapod remains that include crocodylomorphs, rauisuchiforms and sphenodontians. The key elements in the new taxon are the ilium, astragalus, and the humerus, and these exhibit five synapomorphies of Dinosauria. Three of these, namely a largely to fully perforate acetabulum, the presence of a brevis fossa, and a reduced astragalus with an ascending process, are considered to be particularly relevant. The definition and diagnosis of the Dinosauria are restated and the positions of the new form, herrerasaurs and Eoraptor relative to true dinosaurs are discussed.

MESOZOIC THRIPS AND EARLY EVOLUTION OF THE ORDER THYSANOPTERA (INSECTA)

Abstract The oldest known thrips, order Thysanoptera, are described from the Late Triassic of Virginia and Kazakhstan: Triassothrips virginicus Grimaldi and Fraser, new genus and species (Cow Branch Formation: Carnian), and Kazachothrips triassicus Shmakov, new genus and species (Tologoy Formation: Carnian–Norian). Prior to this the oldest definitive thysanopterans were from the Late Jurassic of Kazakhstan (Kimmeridgian), some 80 My younger. Well-preserved, relatively complete, wing venation indicates the Triassic thrips are phylogenetically the basalmost thysanopterans, and their venation even allows identification and homologizing the highly reduced veins in Recent thrips. Another basal thrips is described from mid–Cretaceous (Turonian) amber of New Jersey, Cretothrips antiquus Grimaldi, new genus and species, which is similar to several Recent genera of Aeolothripidae. A phylogenetic hypothesis of basal relationships in Thysanoptera based on wing venation supports a basal relationship for Aeolothripidae and derived position for Phlaeothripidae among Recent families.

Leehermania prorova, the earliest staphyliniform beetle, from the late Triassic of Virginia (Coleoptera: Staphylinidae).

ABSTRACT The Staphylinidae contain over 57,000 described species, thus comprising one of the largest families in all Insecta. Leehermania prorova Chatzimanolis, Grimaldi, and Engel, new genus and species, is described, which is the earliest staphylinid and the oldest definitive polyphagan beetle. The new species is based on a series of well-preserved specimens from the early Norian to late Carnian-aged (Late Triassic) Cow Branch Formation of southern Virginia. It is considered to be subfamily incertae sedis within Staphylinidae, but its possible affinity with the tachyporine group of staphylinids is noted. A summary of all Mesozoic Staphylinidae is provided and the evolutionary history of the lineage briefly discussed.

The skeletal anatomy of the triassic protorosaur Dinocephalosaurus orientalis Li, from the Middle Triassic of Guizhou Province, southern China

Abstract The first protorosaur from the Middle Triassic of China, Dinocephalosaurus orientalis Li is known from two specimens: the holotype (an isolated skull in association with the first three cervical vertebrae), and a referred specimen (an almost complete, associated and partially articulated specimen lacking the tail). This material is here described in detail. A complete and amended diagnosis is given for the genus and its only known species. Among protorosaurs, Dinocephalosaurus is the taxon exhibiting the greatest degree of skeletal paedomorphosis, indicating fully aquatic habits.

THE EARLIEST KNOWN MEMBER OF THE RORQUAL—GRAY WHALE CLADE (MAMMALIA, CETACEA)

Abstract Eobalaenoptera harrisoni, gen. et sp. nov., is described from a partial skeleton collected from the middle Miocene Calvert Formation of Virginia. Characteristics of this taxon, particularly of the petrosal, indicate that the new whale is a member of the clade that includes the Balaenopteridae (rorquals) and Eschrichtidae (gray whales) to the exclusion of “cetotheres” and the Balaenidae (right whales). Some of the probable synapomorphies of this clade include an elongate pars cochlearis, a tubular internal auditory meatus, the greater petrosal nerve foramen on the tympanic side of the petrosal, the stylomastoid fossa extending onto the posterior process of the petrosal, no medial groove on the pars cochlearis, four digits on each forelimb, depressed supraorbital processes, and ascending processes of maxillae extending onto the vertex. The approximate 14-million-year age of the specimen makes it the oldest known member of the clade by some 3 to 5 million years, and extends the fossil record of this clade closer to the divergence time estimated by some recent molecular studies.

DATING BORNEO'S DELTAIC DELUGE: MIDDLE MIOCENE PROGRADATION OF THE MAHAKAM DELTA

ABSTRACT Borneos geologic and paleontological history remains poorly understood because of the lack of outcrops and difficulties with dating. Urban development around the city of Samarinda has produced over four kilometers of well-exposed stratigraphy depicting the progradation of the ancient Mahakam river delta across the Samarinda area, which includes slope, shelf, and deltaic deposits (clastic and carbonate). Previous studies have preliminarily dated the succession as middle Miocene, but reworking and the scarcity of diagnostic fossils make dating difficult. In this paper, an integrated stratigraphic age model has been constructed for the middle Miocene of the Samarinda region with a combination of magnetostratigraphy, sequence stratigraphy, and biostratigraphy (nannofossil, planktonic foraminifera, and larger benthic foraminifera). This age model provides improved temporal constraints for part of the Mahakam Delta succession. It also helps to place the pattern of biodiversity changes seen in Indonesian reef communities into a better time perspective, and permits more accurate sedimentation rates to be determined. It may also serve as a reference point to compare other Neogene sections in Southeast Asia. The two reef complexes at Samarinda, the Batu Putih and the Stadion section, are magnetostratigraphically dated at ∼ 15 Ma and 11.6 Ma, respectively. The new chronology for the Samarinda succession shows that the Mahakam Delta went through a major phase of buildout and progradation during the middle and earliest late Miocene, during which time progradation across the former shelf break took place in the Samarinda area.

Tanystropheus cf. T. longobardicus from the Early Late Triassic of Guizhou Province, Southwestern China

ABSTRACT The protorosaur Tanystropheus longobardicus is well known from the Middle Triassic of alpine Europe. It has been described on the basis of a number of specimens that apparently range from juvenile to adult. The largest specimens have a total body length of approximately 3 m. Here we report on the first occurrence of a large tanystropheid from the Middle or early Late Triassic of southwestern China. The new specimen is indistinguishable from the largest specimens of T. longobardicus from Europe, although it lacks a skull. Both the Chinese specimen here described and the European specimens of T. longobardicus are characterized by 13 cervical vertebrae (not 12 as had previously been assumed). The new find, together with a recent specimen of Macrocnemus from Yunnan Province, highlight shared elements of the vertebrate fauna around the coastline of western and eastern Tethys during Middle to Late Triassic times.

A NEW PROTOROSAUR (DIAPSIDA) FROM THE UPPER BUNTSANDSTEIN OF THE BLACK FOREST, GERMANY

Abstract A new genus and species of protorosaur is described on the basis of material originally referred to Tanystropheus antiquus from the Upper Buntsandstein of the Black Forest, Germany. The new taxon is characterized by eight cervical vertebrae that bear markedly elongate cervical ribs, a shagreen of denticles covering the vomers, palatines and pterygoids, a bifurcate second sacral rib, a well-ossified tarsus with three distal tarsals, and an elongate proximal phalanx on digit five. The status of Tanystropheus antiquus is discussed and, while it is retained, its validity is questioned.

A taxonomic and biostratigraphic re-evaluation of the Post Quarry vertebrate assemblage from the Cooper Canyon Formation (Dockum Group, Upper Triassic) of southern Garza County, western Texas

The Post Quarry, within the lower part of the type section of the Upper Triassic Cooper Canyon Formation in southern Garza County, western Texas, contains a remarkably diverse vertebrate assemblage. The Post Quarry has produced: the small temnospondyl Rileymillerus cosgriffi; the metoposaurid Apachesaurus gregorii; possible dicynodonts and eucynodonts; a clevosaurid sphenodontian; non-archosauriform archosauromorphs (Trilophosaurus dornorum, simiosaurians, and possibly Malerisaurus); the phytosaur Leptosuchus; several aetosaurs (Calyptosuchus wellesi, Typothorax coccinarum, Paratypothorax, and Desmatosuchus smalli); the poposauroid Shuvosaurus inexpectatus (“Chatterjeea elegans”); the rauisuchid Postosuchus kirkpatricki; an early crocodylomorph; several dinosauromorphs (the lagerpetid Dromomeron gregorii, the silesaurid Technosaurus smalli, a herrerasaurid, and an early neotheropod); and several enigmatic small diapsids. Revised lithostratigraphic correlations of the lower Cooper Canyon Formation with the Tecovas Formation, the occurrence of Leptosuchus, and the overall composition of the assemblage indicate that the Post Quarry falls within the Adamanian biozone, and not the Revueltian biozone. Stratigraphic subdivision of the Adamanian biozone may be possible, and the Post Quarry may be correlative with the upper part of the Adamanian biozone in Arizona. The age of the Post Quarry assemblage is possibly late Lacian or earliest Alaunian (late early Norian or earliest middle Norian), between 220 and 215 Ma.