Triassic Genus Research Articles

A new species of the Triassic genus Ideliopsina (Grylloblattida: Ideliidae) from the Ominé locality (Momonoki Formation, southwest Japan)

A new species of Grylloblattida, Ideliopsina aristovi sp. nov., is described from the Upper Triassic Ominé locality (Momonoki Formation, Mine Group, Japan). It belongs to a typical Triassic genus, Ideliopsina Storozhenko, 1996, which species have been previously reported from the Kyrgyz Republic and the Kazakhstan in Central Asia. The new species shows that the corresponding family, the Ideliidae ranging from the Cisuralian to the Late Triassic, remained widely distributed during the latter period, before its extinction.

Mesodiphthera Tillyard, 1919, from the Late Triassic of Queensland, the oldest cicada (Hemiptera: Cicadomorpha: Cicadoidea: Tettigarctidae).

New specimens of its type species from the Queensland Late Triassic (Norian) (~227-~208.5 Ma) fossil insect locality at Dinmore have revealed that the old and obscure Late Triassic genus Mesodiphthera Tillyard, 1919, from nearby Denmark Hill, is a tettigarctid cicada, the earliest record of the family and the oldest cicada. The genus is distinguished by the combined presence of three characters: the primary forks of R and M at about the same level, midway between the basal cell and the nodal line; RA2 with four or five terminal branches; and the inter-medial cross-vein backwardly inclined, running between M2 and M3. Of the three species originally ascribed to Mesodiphthera by Tillyard, only its type, M. grandis Tillyard, 1919, is retained in the genus. The other two species differ significantly from the type and are transferred to Tardilly gen. nov., which is similar to Mesodiphthera in the more or less aligned primary forks of R and M placed at about midway between the basal cell and the nodal line, and the backwardly inclined inter-medial cross-vein which runs between M2 and M3. It differs, however, in its smaller size, broader costal space, three-branched M3+4, and differently shaped CuA and CuA2. The new material, all of which is of M. grandis, provides a complete picture of the shape, colour and venation of its tegmen, whereas Tardilly prosboloides (Tillyard) comb. nov., 1922 and Tardilly dunstani (Tillyard) comb. nov., 1922 are still known only from their poorly preserved type specimens. Mesodiphthera and Tardilly exhibit a number of presumed plesiomorphies, viz the costal space much wider than the CuA cell, the basal cell strongly narrowed apically, and the post-nodal cross-vein series closer to the nodal line than the apex, which place it in the probable paraphyletic subfamily Cicadoprosbolinae. A more informed assessment of their relationships, however, must await a comprehensive analysis of the now 29 fossil genera of the family. The Tettigarctidae were the only cicadas of the Mesozoic and the discovery in the Triassic of Australia of Mesodiphthera and Tardilly clearly distinct from the 24 previously known Mesozoic genera, further demonstrates the family's high degree of structural diversity, and emphasises its almost world-wide distribution in that Era.

An Early Triassic (Dienerian) microgastropod assemblage from the Salt Range, Pakistan and its implication for gastropod recovery from the end-Permian mass extinction

A single limestone sample from the Early Triassic (late Dienerian) of the Salt Range in Pakistan has yielded numerous small gastropods (smaller 2 mm), few bivalves and abundant ammonoids. The limestone is interpreted as a tempestite. Many of the gastropods are extremely well-preserved including protoconch preservation and micro-ornaments. Five species of gastropods are present: (1) isolated larval shells representing a neritimorph taxon of the family Trachyspiridae, (2) early juvenile and larval specimens of the caenogastropod Strobeus pakistanensis, (3) the new caenogastropod species Coelostylina hydrobifomis Nutzel & Ware, (4) the new heterobranch genus and species Eographis microlineata Ntitzel & Ware representing the earliest occurrence of the extant family Hyalogyrinidae (Valvatoidea), (5) the heterobranch Sinuarbullina sp., a genus which originates in the Early Triassic and has also been reported from China, Spitsbergen and the US. Three genera (trachyspirid. Strobeus and Coelostylina) represent survivors from the end-Permian mass extinction whereas Eographis and Sinuarbullina have their earliest known occurrence in the Early Triassic. Eographis is the first Early Triassic genus for which coaxial larval heterostrophy is shown. Together with the Devonian genus Palaeocarboninia and the Carboniferous genus Heteroaclisina, it witnesses a high age of Ectobranchia (living families Hyalogyrinidae, Valvatidae. Comirostridae and Xylodisculidae). This supports the assumption that this group is the first extant offshoot of the Heterobranchia. The studied assemblage is strongly dominated by Strobeus pakistanesis. The small size of the gastropods reflects their ontogenetic stage (early juvenile and larval shells) as well as a small adult size in some of the species. Most of the present gastropods had planktotrophic larval development providing further evidence against the hypothesis that the end-Permian mass extinction event selected against larval planktotrophy. Failure to grow to a larger size or to perform metamorphosis suggests unfavourable living conditions in the source community probably due to oxygen deficiency prior to transport by storm. Size sorting is seen as less likely because the limestone is poorly sorted with relatively large ammonoids being present in considerable numbers. The studied sample yielded also three bivalve taxa amongst them two species representing the genera Leptochondria and Crittendenia.

New Triassic teleosts (Actinopterygii, Teleosteomorpha) from northern Italy and their phylogenetic relationships among the most basal teleosts

ABSTRACT This study provides new evidence of the diversity of Middle–Late Triassic teleosts with the description of new pholidophorids from Italy. The results of the phylogenetic analysis confirm the sister-group relationship [†Aspidorhynchiformes + †Pachycormiformes] as members of Teleosteomorpha and †Prohalecites as the oldest teleosteomorph. The apomorphy-based Teleostei includes a new interpretation of †Pholidophoriformes as a monophyletic group supported by numerous synapomorphies and comprising two families, †Pholidophoridae and †Eurycormidae, fam. nov. The latter is only known from the Upper Jurassic of Europe. The monophyletic family †Pholidophoridae is known by about a dozen European taxa and a Middle Triassic genus (†Malingichthys) from southern Asia, which is the oldest member of the family. The addition of new pholidophorids provides a new interpretation of the possible relationships and taxonomic arrangements within the family †Pholidophoridae. The genera †Pholidorhynchodon and †Eopholidophorus stand as pholidophorids with a unique morphology of the upper oral margin, including a median rostral bone bearing a few large conical teeth, laterodermethmoids armed with large teeth, and the premaxillae displaced from the middle region of the oral margin. This study confirms previous hypotheses of character evolution among basal members of Teleostei, with implications for holostean character evolution. The synapomorphies shared by crown-group Teleostei appeared stepwise more than 140 million years ago over many speciation events and did not arise in a single ancestral species. The analyses of character distribution reflect the gradual accumulation of features that diagnose the crown group. http://zoobank.org/urn:lsid:zoobank.org:pub:0CBDA307-1DD5-4D18-A539-F066E7BF13DC SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: Arratia, G. 2017. New Triassic teleosts (Actinopterygii, Teleosteomorpha) from northern Italy and their phylogenetic relationships among the most basal teleosts. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1312690.

New fossil Osmylopsychopidae (Neuroptera) from the Early/Middle Jurassic of Kyrgyzstan, Central Asia.

Four genera and four species of Osmylopsychopidae are described from the Jurassic of Kyrgyzstan, Central Asia: Oligophlebiopsis biramosa gen. et sp. nov. (Early Jurassic of Sogyuty); Osmylopsychoides anteromedialis gen. et sp. nov., Psychostoechotes undulatus gen. et sp. nov. and Osmylopsychostoechus sogulensis gen. et sp. nov. (all from the late Early to early Middle Jurassic of Sai-Sagul). By their poorly-developed outer gradate series of crossveins, these taxa (except O. anteromedialis gen. et sp. nov.) are more similar to Triassic genera than to the Middle/Late Jurassic Osmylopsychopidae (particularly from Daohugou, China). Two isolated hind wings from Sai-Sagul (i.e., Osmylopsychostoechus sp. and Osmylopsychopidae gen. et sp. indet.) are preliminarily assigned to this family.

Using abundance data to assess the relative role of sampling biases and evolutionary 2 radiations in Upper Muschelkalk ammonoids

The Middle Triassic ammonoid genus Ceratites diversified spectacularly within the Germanic Muschelkalk Basin during the Anisian/Ladian (244–232 Mya). Previous studies have interpreted this diversification as a sequence of rapid, endemic radiations from a few immigrant taxa. Here we investigate the possibility that geological and sampling biases, rather than ecological and evolutionary processes, are responsible for this pattern. A new specimen-based dataset of Ceratites species-richness and abundance was assembled. This dataset was combined with 1:200 000 geological maps in a geodatabase to facilitate geospatial analyses. One set of analyses compared species richness per geological map with the number of occurrences and localities per map. Per-map change in the amount of rock available to sample for fossils was also included as a variable. Of these three variables, number of occurrences is the most strongly correlated with richness. Variation in the amount of rock is not a strong determinant of species-ri...

The Triassic dicynodont Kombuisia (Synapsida, Anomodontia) from Antarctica, a refuge from the terrestrial Permian-Triassic mass extinction

Fossils from the central Transantarctic Mountains in Antarctica are referred to a new species of the Triassic genus Kombuisia, one of four dicynodont lineages known to survive the end-Permian mass extinction. The specimens show a unique combination of characters only present in this genus, but the new species can be distinguished from the type species of the genus, Kombuisia frerensis, by the presence of a reduced but slit-like pineal foramen and the lack of contact between the postorbitals. Although incomplete, the Antarctic specimens are significant because Kombuisia was previously known only from the South African Karoo Basin and the new specimens extend the taxon's biogeographic range to a wider portion of southern Pangaea. In addition, the new finds extend the known stratigraphic range of Kombuisia from the Middle Triassic subzone B of the Cynognathus Assemblage Zone into rocks that are equivalent in age to the Lower Triassic Lystrosaurus Assemblage Zone, shortening the proposed ghost lineage of this taxon. Most importantly, the occurrence of Kombuisia and Lystrosaurus mccaigi in the Lower Triassic of Antarctica suggests that this area served as a refuge from some of the effects of the end-Permian extinction. The composition of the lower Fremouw Formation fauna implies a community structure similar to that of the ecologically anomalous Lystrosaurus Assemblage Zone of South Africa, providing additional evidence for widespread ecological disturbance in the extinction's aftermath.

Modesticoncha, A new name for Modestella Hautmann, 2001 (Bivalvia, Trigonoida) [non Modestella Owen, 1961 (Brachiopoda, Terebratulida)

Dr. Philippe Bouchet, Muséum national d'Histoire naturelle, Paris, kindly brought to my attention that the name Modestella Hautmann, 2001, which I introduced for a Triassic trigonoid bivalve genus (type species: Trigonia zlambachensis Haas, 1909), is preoccupied by Modestella Owen (in Casey), 1961 (Brachiopoda, Terebratulida). I therefore propose to replace Modestella Hautmann, 2001 by the new name Modesticoncha. The new name derives from the combination modestus (Latin) = modest, referring to the lack of ornamentation, and concha (Latin) = shell.

GUODUNITES, A LOW‐PALAEOLATITUDE AND TRANS‐PANTHALASSIC SMITHIAN (EARLY TRIASSIC) AMMONOID GENUS

Abstract: Based on new, bed‐rock controlled material from Oman and Utah, USA, the Early Triassic genus Guodunites, which was recently erected on the basis of scarce specimens from northwestern Guangxi, South China, is now shown to be a representative of Proptychitidae. This solves the question of the previously unknown phylogenetic affinity of this genus. The genus is restricted to the late middle Smithian, and to date, its biogeographical distribution comprises Oman, South China and Utah, thus indicating an essentially low palaeolatitudinal distribution during the Early Triassic. Its palaeobiogeographical distribution further strengthens the existence of significant equatorial faunal exchanges between both sides of the Panthalassa at that time. It also suggests that, in addition to the potential stepping stones represented by Panthalassic terranes, vigorous equatorial oceanic currents must have contributed largely to the dispersal of ammonoids during such time intervals.

Late Permian dicynodont fauna from Laos

Abstract In Laos, dicynodonts have long been known only from one specimen, now lost, a partial skull discovered by Counillon in the purple beds of the area of Luang Prabang, and initially described by Repelin as Dicynodon incisivum . Subsequent researchers attributed the specimen either to the Late Permian genus Dicynodon or to the Early Triassic genus Lystrosaurus. Recent Franco-Laotian expeditions have gathered, from the same purple beds, a collection of tetrapods composed mainly of dicynodonts. They can all be ascribed to Dicynodon , and the available evidence suggests that the purple beds are Late Permian in age. The genus Lystrosaurus remains unknown in Laos.

Taxonomy and phylogeny of the Triassic bivalve families Mysidiellidae Cox, 1964 and Healeyidae new family

The Mysidiellidae are morphologically isolated among Triassic bivalves but share important characters with Late Paleozoic Ambonychioidea. Apart from a great similarity in the general shape of the shell, the most primitive mysidiellid genus Promysidiella resembles ambonychioids in the presence of a duplivincular-opisthodetic ligament system. Within the Mysidiellidae, this ligament type evolved into the transitional ligament system that characterizes Late Triassic Mysidiella. The phyletic polarity indicates that this evolution probably took place by paedomorphosis. New examinations of the shell microstructure of Mysidiella demonstrate the presence of simple prismatic and possibly foliated structures in the calcitic outer shell layer, which further supports an ambonychioid affinity. Therefore, the Mysidiellidae are removed from the Mytiloidea and assigned to the Ambonychioidea. The poorly known genus Protopis, which was originally included in the Mysidiellidae, probably had a parivincular ligament system and was hence a member of the Heteroconchia. Joannina, which was previously considered a junior synonym of Protopis, is re-established. The hinge margin of Joannina carries a well developed nymph but lacks teeth. These characters as well as its modioliform shape, anterior shell lobe, and pronounced diagonal carina link Joannina with the Late Triassic genus Healeya (Modiomorphoidea). Both taxa are herein placed in the new family Healeyidae, which differs from the morphologically similar Kalenteridae in the absence of elaborated hinge teeth. Protopis, as well as the recently described genera Leidapoconcha, Waijiaoella, and Qingyaniola, are tentatively assigned to the Healeyidae.

A new Middle Triassic genus and species of Mylacridae (Blattodea) from China

A new Middle Triassic genus and species of Mylacridae (Blattodea) from China

A new Middle Triassic genus and species of Mylacridae (Blattodea) from China

Shaanxi Entomofauna is important in the study of insect’s evolution from Paleozoic to Mesozoic. A new genus and species, Cathayiblatta longata gen. et sp. nov., of Mylacridae (Blattodea) from Middle Triassic is described. The new genus and species was found in Tongchuan City, Shaanxi Province of China, and the fossil referred to a new member of Tongchuan Entomassemblage of Shaanxi Entomofauna. The ultrastructure of wing was observed through scanning electron microscope. Comparison was made between the new genus and related genera Hemimylacris and Metaxyblatta.

Precise U–Pb age constraints for end-Triassic mass extinction, its correlation to volcanism and Hettangian post-extinction recovery

New precise zircon U–Pb ages are proposed for the Triassic–Jurassic (Rhetian–Hettangian) and the Hettangian–Sinemurian boundaries. The ages were obtained by ID-TIMS dating of single chemical-abraded zircons from volcanic ash layers within the Pucara Group, Aramachay Formation in the Utcubamba valley, northern Peru. Ash layers situated between last and first occurrences of boundary-defining ammonites yielded 206Pb/238U ages of 201.58±0.17/0.28 Ma (95% c.l., uncertainties without/with decay constant errors, respectively) for the Triassic–Jurassic and of 199.53±0.19 / 0.29 Ma for the Hettangian–Sinemurian boundaries. The former is established on a tuff located 1 m above the last local occurrence of the topmost Triassic genus Choristoceras, and 5 m below the Hettangian genus Psiloceras. The latter sample was obtained from a tuff collected within the Badouxia canadensis beds. Our new ages document total duration of the Hettagian of no more than c. 2 m.y., which has fundamental implications for the interpretation and significance of the ammonite recovery after the topmost Triassic extinction.The U–Pb age is about 0.8±0.5% older than 40Ar–39Ar dates determined on flood basalts of the Central Atlantic Magmatic Province (CAMP). Given the widely accepted hypothesis that inaccuracies in the 40K decay constants or physical constants create a similar bias between the two dating methods, our new U–Pb zircon age determination for the T/J boundary corroborates the hypothesis that the CAMP was emplaced at the same time and may be responsible for a major climatic turnover and mass extinction. The zircon 206Pb/238U age for the T/J boundary is marginally older than the North Mountain Basalt (Newark Supergroup, Nova Scotia, Canada), which has been dated at 201.27±0.06 Ma [Schoene et al., 2006. Geochim. Cosmochim. Acta 70, 426–445]. It will be important to look for older eruptions of the CAMP and date them precisely by U–Pb techniques while addressing all sources of systematic uncertainty to further test the hypothesis of volcanic induced climate change leading to extinction. Such high-precision, high-accuracy data will be instrumental for constraining the contemporaneity of geological events at a 100 kyr level.

The taxonomy of the traversodontid cynodonts Exaeretodon and Ischignathus

This paper addresses some issues about the taxonomy of two traversodontid cynodonts: Exaeretodon. and Ischignathus. The type species of Exaeretodon, a Late Triassic genus, is E. frenguellii, but the valid name of the Argentinian species is E. argentinus. Another species of this genus is E. riograndensis from Brazil. Part of the holotype of Traversodon major from Brazil, that was subsequently allocated in Exaeretodon, as well as Exaeretodon statisticae from India, are considered as indeterminate species of Exaeretodon. After a detailed discussion of the diagnoses of Ischignathus sudamericanus, this taxon is regarded as a junior synonym of Exaeretodon argentinus.

Proharpoceras Chao: a new ammonoid lineage surviving the end‐Permian mass extinction

Based on new, bed-rock controlled material from northwestern Guangxi and Oman, the Early Triassic genus Proharpoceras Chao is shown to be a representative of Otocerataceae. Character analysis excludes a direct link with the Griesbachian Otoceratidae and favours a derivation of Proharpoceras from the late Permian Anderssonoceratidae. The biostratigraphic range of Proharpoceras is restricted to the Smithian and its biogeographic distribution comprises Oman, South China, and Primorye, thus indicating an essentially low palaeolatitudinal distribution. Proharpoceras has no apparent relatives among other Early and Middle Triassic Ceratitida and is thus considered to be the last representative of Otocerataceae. This offshoot of the late Permian Anderssonoceratidae implies that an additional ammonoid lineage survived the end Permian extinction and that it dwindled away for some 2 Myr before going extinct.

Phylogeny of families in the Pectinoidea (Mollusca: Bivalvia): importance of the fossil record

The Triassic fossil record points to the monophyly of the Pectinoidea (scallops), all members of which have a triangular resilium with a nonmineralized medial core that functions below the hinge line. The elastic properties of this resilium in extant taxa predict that the initial adaptation of the Pectinoidea was to swimming. This is indeed corroborated by the shell form of Pernopecten, the earliest known pectinoidean genus, which ranged from late Devonian to earliest Triassic. The new family Entolioididae, a largely Triassic group, provides the missing link between the Pernopectinidae and the families Propeamussiidae, Entoliidae, and Pectinidae, all of which originated by the Middle Triassic and survive to the present day. A new Triassic genus Filamussium shows that the Propeamussiidae originated from the Entolioididae, not directly from the Pernopectinidae as previously supposed. Evidence from morphology, the fossil record, and molecular genetics indicates that the family Spondylidae originated in the Middle Jurassic from an ancestor within the Pectinidae, possibly the genus Spondylopecten, which was already present in the Late Triassic. Journal compilation © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society, 2006, 148, 313–342. No claim to original US government works

CARNIASTER ORCHARDI NEW GENUS AND SPECIES (ECHINODERMATA: ASTEROIDEA), THE FIRST TRIASSIC ASTEROID FROM THE WESTERN HEMISPHERE

Carniaster orchardi n. gen. and sp. (Echinodermata: Asteroidea) is only the fourth Triassic asteroid known from material complete enough to warrant a generic name. Data indicating familial and ordinal positions are not available. All four Triassic genera belong to the exclusively post-Paleozoic crown group. Carniaster does not appear to differ significantly from other described Triassic genera, and it probably represents a broadly basal lineage within the crown group diversification. Available morphological data suggest no ecologic parameters that would be unusual among living asteroids. Carniaster is the first complete Triassic asteroid known from beyond Europe.

The Spores of the Triassic LycopsidPleuromeia sternbergii(MÜnster) Corda: Morphology, Ultrastructure, Phylogenetic Implications, and Chronostratigraphic Inferences

In situ microspores and megaspores from two reference cones of Pleuromeia sternbergii have been investigated. Their morphological and ultrastructural features are compared with those of the spores of another Triassic Pleuromeia species, Pleuromeia rossica, and with those of extant Isoetaceae. These comparisons clearly show that the Triassic and recent spores share a number of features that distinguish the isoetalean spores. Because the walls of both the microspores and megaspores of P. sternbergii were variably damaged owing to their poor preservation and/or low resistance to chemical extraction treatments, their study also proved to be particularly instructive in several other respects. They clearly showed that the “laminated zones”—i.e., the proximal small structural differentiations of the exospore, which initially were known only in living lycopsid microspores—(i) are present in both microspores and megaspores of the Triassic genus Pleuromeia and (ii) correspond to the papillae (cushions, dark spots, ...

RECOGNITION OF THE ASTEROID (ECHINODERMATA) CROWN GROUP: IMPLICATIONS OF THE VENTRAL SKELETON

All known post-Paleozoic asteroids belong to the crown group, and no crown-group asteroid is known from the Paleozoic. A scanty fossil record provides limited data on morphology of both Paleozoic stem-group sister lineages and on the Triassic crown group diversification. Timing of events is weakly constrained. Interpretations based on this meager record are tentative.Within limitations of the record, recent work suggests that skeletal arrangement of the ventral surface offers apomorphies of crown-group diversification. Enlarged disk size is common in the crown group. Large disks are constructed in part by addition of many ventral and ventral-lateral so-called “actinal” ossicles. Actinals in the crown group are comparatively uniform in size, shape, and arrangement within each species. Actinal alignment is of one of two patterns, parallel to adambulacrals or parallel to marginals. Actinals in the crown group are tentatively considered to be an apomorphy of the crown group, although the incomplete fossil record leads to uncertainty.Enlarged disks are found in some Paleozoic (stem-group) asteroids. Axillary ossicles, marginal series extending onto ventral interbrachia, and enlarged disk adambulacrals are modes of disk size increase known only from Paleozoic asteroids. Actinal ossicles are found in a few stem-group species but arrangements are unlike those of the crown group.Certain Carboniferous and Permian genera share aspects of ambulacral column construction with the crown group, but lack actinal apomorphies. Actinal arrangement is available for two of the three known Triassic genera. In certain ways, patterns are intermediate between stem-group and Jurassic and younger crown-group asteroids.