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Geometric morphometric approaches become increasingly applied in the fields of biology and palaeontology. Taxonomy is a good example, where a long‐standing intention of scientists is to eliminate subjectivity as much as possible. In the case of biostratigraphically important conodont elements, the application of such methods is not widespread. Only a handful of studies attempted to deal with the morphological variance of conodont elements from this aspect. The detailed description of five lower Norian (Upper Triassic) taxa (Ancyrogondolella quadrata, A. rigoi, A. triangularis, A. uniformis and Metapolygnathus mazzai) is presented here based on landmarks and Fourier analysis of the P1 element and keel outlines. Both methods led to similar outcomes regarding taxonomic differentiation and exposing shape variability. Consensus shapes were generated to objectively reveal the typical contour shape of each taxon, which allowed their comparison with each other, and with the members of their respective sample population including the holotypes. The results demonstrated that the holotype of a taxon is generally not an average representative, but rather a peripheral form with well separable morphological characteristics. Ancyrogondolella quadrata and A. rigoi turned out to represent a morphological continuum with ample transitional forms between these two end‐members that may cause bias in their biostratigraphic applicability, however their combined shape variance seems to be too large for uniting them into a single species. Given the results that may be too subtle to realize based solely on qualitative observations, future taxonomic studies and type material designation could greatly benefit from the application of similar methodologies. [ABSTRACT FROM AUTHOR]

Abstract: The first tunicates with a calcareous exoskeleton are reported from Late Triassic buildup‐slope deposits of the Dolomites. Although examples of this group have been known since the early 1900s from the middle–upper Permian of eastern Asia and Sicily as Khmeria, they were erroneously attributed to rugose corals. These early representatives are small, double‐valved, conical skeletons, which evolved into multi‐plated capsules with up to 35 opercula. The latter are joined along zigzag margins, which in life could probably be opened for the atrial and branchial siphons. The construction and shape of these skeletons distinguish them from plants or other invertebrate phyla, while they share several similarities with living tunicates, specifically to sessile ascidians. Apart from a soft‐bodied genus from the lower Cambrian of China, ascidians are known only from isolated spicules, which occur sporadically from the Lower Jurassic onwards. The calcareous skeleton of these Late Triassic tunicates consists of aragonitic fibres, which form spherulitic or clinogonal microstructures. It seems that the stellate aragonitic spicules of Jurassic to Recent ascidians are a vestige of Permian–Triassic ancestors, which after the Carnian lost the ability to construct compound solid skeletons but partly still retain a soft double‐valved or multi‐operculate cellulose‐like tunic. The following taxa are described as new: Order Khmeriamorpha with the genera Khmeria Mansuy and Zardinisoma gen. nov., and the following species: Khmeria stolonifera (late Permian), Khmeria minima (Late Triassic), Zardinisoma japonicum (late Permian), Z. cassianum, Z. pyriforme, Z. polyplacophorum and Z. pauciplacophorum (all Late Triassic). [ABSTRACT FROM AUTHOR]

Doswellia sixmilensis is a new species of the dos-welliid archosauromorph genus Doswellia named for an incomplete skeleton from the Upper Triassic Bluewater Creek Formation of the Chinle Group in west-central New Mexico, USA. D. sixmilensis differs from D. kaltenbachi Weems, the type and only other known species of Doswellia, in its larger size, higher tooth count and greater heterodonty, possession of keels on the cervical centra and the presence of discrete knobs or spikes on some osteoderms. The holotype of D. six-milensis is the fourth occurrence of Doswellia and only the second occurrence of a Doswellia skull, which includes the previously unknown premaxilla and maxilla (and therefore the best dentition) and has the best-preserved cervical vertebrae. Although it adds to our knowledge of the anatomy of Doswellia, this new information does not alter previous concepts of the phylogenetic relationships of the doswelliid genera, largely because they are so poorly known anatomically. The genus Doswellia is known from the Newark Supergroup in Virginia, and the Chinle Group in Texas, New Mexico and Utah, in strata of Otischalkian-Adamanian age. The type locality of D. sixmilensis is c. 43 m stratigraphically below a bed from which U-Pb dating of detrital zircons yields a maximum depositional age of c. 220 Ma, so this is a reasonable approximate numerical age for D. sixmilensis. [ABSTRACT FROM AUTHOR]

We document here a new taxon of sphenodontian, Whitakersaurus bermani gen. et sp. nov., that is also the most complete sphenodontian fossil from the Upper Triassic Chinle Group in the south-western USA and the first Chinle sphenodontian represented by more than a single fragmentary dentulous element. The holotype was recovered during preparation of block C-8-82 from the famous Coelophysis (Whitaker) quarry at Ghost Ranch, New Mexico, and is the most complete small vertebrate recovered from the quarry. Detailed lithostratigraphy and geologic mapping demonstrate that the Whitaker quarry is in the Rock Point Formation of the Chinle Group, so Whitakersaurus is the first sphenodontian reported from this unit. Records of the phytosaur Redondasaurus at the quarry and elsewhere in the Chinle Group demonstrate that the quarry, and thus Whitakersaurus, is of Apachean (late Norian–Rhaetian) age. The sphenodontian specimen consists of incomplete left and right dentaries, a partial left? maxilla?, and impressions of a probable palatal element, all of which preserve multiple teeth. Whitakersaurus is distinct from other sphenodontians in possessing a unique combination of the following features: marginal dentition pleurodont anteriorly and posteriorly acrodont; pronounced heterodonty in dentary, with as many as 15 smaller, peg-like teeth anteriorly and several larger, posterior teeth that are conical and striated; faint radial ornamentation of posterior tooth crowns; presence of c. 19 dentary teeth; and absence of a distinct flange on posterior teeth. Numerous other details distinguish it from both more primitive and more derived taxa. Whitakersaurus, therefore, helps to document further mosaic evolution and an extensive diversification event of sphenodontians during Triassic time. Although sphenodontian taxa are relatively easily recognized, widely distributed, and common small- or microvertebrate fossils, the long stratigraphic ranges of taxa known from multiple specimens hinders their utility as index fossils with which to correlate strata across Pangaea. [ABSTRACT FROM AUTHOR]

Species of marine bivalves of the pectinoid genus Monotis provide useful biochronologic indices for the Late Triassic (middle Norian–earliest Rhaetian). We report the succession of Monotis at Hernstein in Lower Austria where typical late Norian Monotis salinaria (Schlotheim) are overlain by strata with apparently the youngest Monotis known of demonstrable Rhaetian age: Monotis hoernesi Kittl and Monotis rhaetica sp. nov., a species closely related to M. rudis Gemmellaro. A Rhaetian (Sevatian 2) age is confirmed by the co-occurrence of Monotis with the platform conodont Misikella posthernsteini and close association with the ammonoid Paracochloceras. A review of late Norian monotid species indicates that a profound extinction event occurred in the pelagic realm at or close to the Norian/Rhaetian boundary where c. 15 monotids ( Monotis s.l. and Maorimonotis) became extinct. The surviving Monotis are dwarfed when compared to their Norian predecessors and may represent an ecological/phylogenetic response to the crisis. [ABSTRACT FROM AUTHOR]

In the 1970s the Upper Triassic strata of the Argana Basin yielded archosaurian remains that were tentatively attributed to the rauisuchian Ticinosuchus. Restudy of this material together with new remains reveal new anatomical data and show that it in fact belongs to a new taxon, Arganasuchus dutuiti gen. et sp. nov. The systematics of the Rauisuchia are still unresolved; nevertheless, a monophyletic suprageneric group can be defined within the probable non-monophyletic rauisuchians. Arganasuchus dutuiti differs from all adequately known rauisuchians in three autapomorphies: acetabular rim on pubis runs anteroventrally parallel to pubic shift rather than being terminal and perpendicular to it; large contribution of pubis to acetabular depression; palatal process of maxillary low and confluent with interdental crest, rather than separated from it by a large area. The maxilla of Arganasuchus resembles those of Batrachotomus and Fasolasuchus in having a Y-shaped rather than a U-shaped form. As in rauisuchids, Arganasuchus dutuiti has short cervical vertebrae and a dorsal border of the proximal extremity of the pubis that is convex in lateral view. It shares one derived character state with Batrachotomus and Postosuchus (a tear-shaped and anteriorly orientated rugosity on the lateral side of the pubis, lying on a deep, longitudinal depression) and one more derived character state with Batrachotomus (narrow ante-acetabular part of the pubis; hence, the anterior border of the proximal extremity of the pubis is almost contiguous with the actabular rim). [ABSTRACT FROM AUTHOR]

Diverse freshwater aquatic palynomorphs are present among rich terrestrial palynofloras from the upper part of the Potrerillos and Cacheuta formations outcropping in the Cuyana Basin at the southern extremity of the Precordillera of Argentina. The Potrerillos/Cacheuta sequence includes fluvial, deltaic and lacustrine facies deposited in the early Late Triassic fault-bounded syn-rift Cacheuta hemigraben. The phytoplankton described and illustrated consist of representatives of colonial chlorococcalean algae belonging to the Hydrodictyaceae ( Plaesiodictyon) and Botryococcaceae ( Botryococcus), a diverse group of Zygnemataceae zygospores, a freshwater dinoflagellate cyst ( Bosedinia) and acritarchs (sphaeromorphs). Zygnematacean zygospores are represented by species of Gelasinicysta?, Lecaniella, Mougeotia, Ovoidites, Peltacystia and Schizocystia. Of these, Gelasinicysta? cuyanensis sp. nov. is newly described. Quantitative analysis of the palynofloras permits interpretation of changes in the local vegetation and phytoplankton communities controlled by changes in environmental setting. Two algal associations are recognized as belonging to different stages in the evolution of the basin. Diverse zygnematacean assemblages along with hydrodictyacean, botryococcacean and leiosphere/sphaeromorph algae are common in fluvial–deltaic environments of the upper part of the Potrerillos Formation and the lowermost part of the Cacheuta Formation. Higher in the sections (in the Cacheuta Formation) Botryococcus dominates, in association with amorphous kerogen, representing deposition in a relatively deep, quiet-water, lacustrine environment where anoxic conditions prevailed. In the Cacheuta hemigraben the lacustrine shales have average TOC values of 4 per cent (locally reaching 20 per cent), with some terrigenous components (Type II/III kerogen), but dominant amorphous, algal-like, organic matter (Type I/II kerogen). Oils derived from these source rocks are predominantly waxy. [ABSTRACT FROM AUTHOR]

The first abundant, well-preserved fossils of the unusual archosauromorph reptile Trilophosaurus jacobsi Murry are from an Upper Triassic bonebed in the lowermost Trujillo Formation of the Chinle Group in Borden County, Texas. A nearly complete left side of the skull and incomplete but articulated mandible of a juvenile individual demonstrate that Trilophosaurus jacobsi Murry is referable to Trilophosaurus, so the putative procolophonid genus Chinleogomphius is a junior objective synonym of Trilophosaurus. Features of T. jacobsi that diagnose it from T. buettneri include asymmetrical, tricuspate teeth in which the central cusp is taller than the marginal cusp, polygonal in cross-section and displaced slightly lingually; the lingual cusp is low, transversely broadened and anteroposteriorly compressed; teeth with prominent cingula along the mesial and distal margins; and paired sagittal (parasagittal) crests composed of portions of the postfrontals and the parietals, as well as a relatively broad skull roof between the supratemporal fenestrae. We also re-illustrate and re-describe the holotypes of both Trilophosaurus buettneri Case and T. jacobsi Murry. T. jacobsi is primarily Adamanian in age, and the lowest occurrence of T. jacobsi is stratigraphically above that of T. buettneri. Therefore, T. buettneri is an Otischalkian–Adamanian index taxon, and T. jacobsi is an Adamanian–?earliest Revueltian index taxon. Trilophosaurus teeth are readily identifiable to species and therefore identifiable as isolated fossils. [ABSTRACT FROM AUTHOR]