Biostratigraphic Implications Research Articles

Biostratigraphic implications of the Valanginian to Lower Hauterivian benthic foraminifers from the Vergol/La Charce composite Section (southeast France, Vocontian Basin)

The well-exposed Valanginian to Lower Hauterivian sequences of the Vocontian Basin (South-East France) are revisited based on a micropalaeontological study of material collected in the Vergol and La Charce sections. A total of 528 tests of benthic foraminifers were recorded in good state of preservation. A biometric analysis of the species Dorothia hauteriviana is proposed in order to identify its morphotypes and their biostratigraphic significance. This study aims to identify benthic foraminiferal assemblages and to propose an integrated biostratigraphy along the Valanginian to Hauterivian sequence of the Vergol and La Charce sections (Vocontian Basin). Two foraminiferal assemblages have been recognized. The Lenticulina nodosa foraminiferal assemblage ranges from the lower Valanginian to the basis of the upper Valanginian Saynoceras verrucosum ammonite standard zones (StZ). The Lenticulina busnardoi foraminiferal assemblage is recorded from the second half of S. verrucosum to the top of Neocomites peregrinus StZ. The current study shows that the Vergol and La Charce composite section represents a complete segment of Valanginian to Lower Hauterivian foraminiferal assemblages, and records several changes in taxonomic biodiversity and dynamics of population for this interval.

First palynological evidence from the Upper Devonian of Armenia (northern Gondwanan margin): biostratigraphic implications

Diverse and abundant terrestrial palynomorphs are recovered from the shales in the Frasnian–Famennian succession of the Ertych section situated in central Armenia. They represent the first discovery of spores from the Upper Devonian shallow marine sedimentary sequences of the South Armenian Block, which at that time was part of the northern Gondwanan continental margin. Their taxonomic assessment recognizes 37 spore taxa assigned to 22 genera. Notably, the presence of Teichertospora torquata allows us to assign the entire studied succession to the torquata–gracilis zone, indicating a late Frasnian to early Famennian age. In addition, the occurrence of Acinosporites lindlarensis, which corresponds to the spores of the herbaceous lycophyte Leclercqia, suggests that the age of the studied succession should be further restricted to the late Frasnian. The presence of chitinozoans (i.e., Angochitina mourai) in the studied interval argues for marine deposition. Our biostratigraphic results provide a more coherent picture for the sedimentary evolution of this Frasnian–Famennian sequence arguing for a rather uninterrupted sedimentation close to the critical boundary interval. The identified spore assemblage highlights the close affinity of the Frasnian vegetation preserved in Armenia with other parts of the Northern Gondwana and southern Laurentia. We provide the first evidence of the occurrence of Kraeuselisporites ollii outside Canada and extend its known age range to late Frasnian.

Palynological variability within the Permian (Changhsingian) Umm Irna Formation (Jordan): implications for biostratigraphy and fluid-flow character in alluvial formations

The Permian (Changhsingian) Umm Irna Formation (Jordan) yields important plant fossils that have influenced our understanding of the early evolution of plants that later dominated the vegetation of the Mesozoic. The formation was deposited in a fluvial regime characterised by the co-occurrence of stacked small-scale braided channels and of larger, higher-sinuosity channels with deposition on point bars, all intercalated into a heterogeneous background sedimentation of finer-grained floodplain deposits, including stacked crevasse-splay deposits, interspersed abandoned-channel and oxbow-lake fills, and lenses of peaty back-swamp deposits. Here, we document the remarkable compositional variability expressed in 124 palynomorph assemblages that were recovered from different argillaceous deposits in the Umm Irna Formation within a ∼2 km2 outcrop area around a major meandering channel. Our results reveal lateral and vertical variation within individual argillaceous units, as well as lateral variation between different argillaceous units in the same sedimentary complex at similar stratigraphic levels. When combined with plant macrofossil data, the results show that variability in the palynological content may be influenced mainly by two factors. The first is connectedness to the major channel; the drainage system carried a mixture of palynomorphs from across the floodplain but also from a large hinterland of tributaries draining higher parts of the floodplain and uplands beyond to the south and east. The second is the influence of local vegetation communities on the floodplain which would likely be more marked in less connected parts of the floodplain. These findings have implications for the palynological study of alluvial sequences of the Palaeozoic and Mesozoic, and for understanding the ability to identify mudstone units via palynological fingerprinting. Such individual units are of great importance as baffles to fluid flow in reservoirs that might be used for oil and gas, low-temperature geothermal energy storage, carbon capture and storage, and hydrogen storage in alluvial successions.

Stranger in the nest: On the biostratigraphic relevance of a new record of a traversodontid cynodont in southern Brazil (Candelária Sequence, Upper Triassic)

The Várzea do Agudo is an Upper Triassic site of the Candelária Sequence of Southern Brazil that boasts an extensive fossil record. It is assigned to the Exaeretodon subzone of the Hyperodapedon AZ (mid-late Carnian) mainly due to the prevalent presence of the traversodontid Exaeretodon riograndensis — up to now the sole traversodontid discovered at the site. In this study, we report the first record of the traversodontid Siriusgnathus niemeyerorum in the Várzea do Agudo site. The new specimen was excavated from the upper layers of the outcrop. Its identification as S. niemeyerorum is substantiated by diagnostic features such as a poorly developed interorbital depression, an inconspicuous suborbital process of the jugal, a not deeply concave base of the lambdoidal crest, the distal accessory labial cusp of the upper postcanines more labially oriented than E. riograndensis, and two upper incisors — so far, a trait autapomorphic to the species among traversodontids. The age of the type locality of S. niemeyerorum has been a subject of debate. Whereas the Siriusgnathus-bearing sites had been associated with younger levels than those of the Hyperodapedon AZ, the absence of index fossils hampered proper biostratigraphic approaches. The finding of a S. niemeyerorum specimen in the same site as E. riograndensis poses a challenging scenario for the biostratigraphy of the fossiliferous outcrops of the municipality of Agudo. It is noteworthy, however, that the new specimen was excavated above the layers yielding E. riograndensis. This raises the question of whether the fossiliferous stratum of the Várzea do Agudo site was deposited in a single event or in a short period, or if it reflects two different time horizons. In the case of the latter, the existence of early Norian sites with distinct faunal composition near the Siriusgnathus-bearing sites could imply the existence of an intermediate fauna between this AZ and the Exaeretodon subzone of the Hyperodapedon AZ, of which S. niemeyerorum would be a constituent. Considering this context, this study discusses the possible biostratigraphic implications of the new record for the biostratigraphy of the sites of the Candelária Sequence.

A new Late Ordovician bubble-headed trilobite species from South West Wales and its implications for biostratigraphy

A new Late Ordovician bubble-headed trilobite species from South West Wales and its implications for biostratigraphy

Palynology and palynofacies of the Permian Paso Aguiar and Yaguarí formations (Paraná Basin, Uruguay): Paleoclimatic, paleoenvironmental, and biostratigraphic implications

The palynological information of the Paso Aguiar Formation (Paraná Basin, Uruguay) is scarce, and the overlying Yaguarí Formation has been hitherto considered as barren. In this study, the palynology and palynofacies of 17 samples recovered from borehole DINAMIGE 943 “Estancia El Águila”, drilled in the Cerro Largo Department (northeastern Uruguay), are analyzed. Palynological assemblages are dominated by striate bisaccate pollen grains, mainly those assigned to the genera Staurosaccites and Lueckisporites, and subordinated apiculate monolete and cingulizonate-cavate spores, essentially represented by Thymospora and Lundbladispora, Gondisporites, and Spelaeotriletes, respectively. The assemblages also include non-taeniate bisaccate and plicate-colpate pollen grains, laevigate and apiculate trilete spores, and algae. Moreover, laevigate monolete spores, non-taeniate and taeniate monosaccate pollen grains, and acritarchs are present in low quantities. The diverse palynoassemblages constitute evidence of a source palaeoflora primarily composed of gymnosperms, with important contributions from glossopterids and conifers. This is complemented by sub-dominant ferns and lycophytes, implying seasonally warmer and humid climates. The palynofacies analysis suggests marine depositional environments with terrestrial inputs related to fluvio-deltaic discharges. Proximal-distal variations are inferred for the lower and middle levels of the Paso Aguiar Formation, while high-energy proximal marine settings with variable redox conditions are deduced for the upper Paso Aguiar Formation and the lower Yaguarí Formation. The abundance of spores recorded is noteworthy, particularly when considering the environmental interpretations for these units. However, the influence of differences in preservation among palynomorphs cannot be entirely ruled out. The assemblages are assigned to the Striatoabieites anaverrucosus-Staurosaccites cordubensis Zone of the Paraná Basin in Uruguay. Nevertheless, obtaining additional data from the studied geological units is crucial to enhance and fine-tune the existing palynostratigraphic framework. Considering the radiometric ages available for the Paraná Basin, along with the ages proposed for comparable biozones in the region and assemblages from correlative units in Brazil, a late Cisuralian–late Guadalupian (Kungurian to Capitanian) age is suggested for the studied section.

First record of Macrocollum itaquii (Dinosauria: Sauropodomorpha) outside the type locality and its biostratigraphic significance

ABSTRACT The early radiation of dinosaurs was an evolutionary event characterized by distinct episodes. While the earliest unequivocal records are from Carnian strata and relatively well-documented, the subsequent moment of dinosaur radiation is poorly studied. The fossil record of early Norian dinosaurs from Brazil provides one of the best samples regarding the dawn of the “Prosauropod Empire”. In the present study, we describe the first occurrence of Macrocollum itaquii outside its type locality and discuss its biostratigraphic implications. This dinosaur is of particular interest due to its significance as the oldest sauropodomorph with an elongated neck, expressing the typical body plan seen in post-Carnian sauropodomorphs. The new specimen consists of a partial posterior autopodium, sharing anatomical features exclusively with M. itaquii among sauropodomorphs. The presence of this unaysaurid at the “Boi da Guampa Torta” site allows the biostratigraphic correlation with the “Wachholz” site. According to the phylogenetic affinities of M. itaquii (which is more derived than Pampadromaeus barberenai and Bagualosaurus agudoensis), both fossiliferous sites are younger than the “Várzea do Agudo” site. Nevertheless, further specimens are necessary in order to determine the position of the sites with M. itaquii in relation to the other surrounding outcrops (i.e., Siriusgnathus-bearing outcrops).

First record of the late Famennian conodonts in Qamdo, Tibet and their biostratigraphic implications

Based on the conodonts recovered for the first time and some brachiopods, this study revises the age of the Wuqingna Formation in eastern Tibet to a late Famennian, challenging prior Carboniferous classification based on coral assemblages. In this study, conodonts are described for the first time from the Wuqingna Formation on the Wuqingka Mountain near Toba Town, Qamdo City in eastern Tibet. The conodont assemblage contains 6 species/subspecies (including morphotypes within open nomenclature) that belong to three genera. The conodont species Polygnathus cf. perplexus, Po. homoirregularis, Po. wuqingnaensis n. sp. and Scaphignathus peterseni suggest an age of late Famennian, probably the Palmatolepis gracilis manca Zone to the Pa. gr. expansa Zone, for the lower part of the Wuqingna Formation, which was previously assigned to the Carboniferous based on the rugose coral assemblages.

Eocene sediments and a fresh to brackish water biota from the early rifting stage of the Upper Rhine Graben (west of oil field Landau, southwest Germany): implications for biostratigraphy, palaeoecology and source rock potential

Eocene sediments and a fresh to brackish water biota from the early rifting stage of the Upper Rhine Graben (west of oil field Landau, southwest Germany): implications for biostratigraphy, palaeoecology and source rock potential

Middle-late Eocene to Early Miocene micropaleontology of the ANH–TIERRALTA–2–X–P well: Biostratigraphic implications for southwestern deposits of the Sinú-San Jacinto belt (Colombian Caribbean)

The Eocene and Oligocene deposits of the southwestern region of the Sinú-San Jacinto Belt (SSJB) in NW South America were formed in marine environments influenced by fluvial discharges from the northern Andes of Colombia. However, these deposits are not well-exposed on the surface, which has limited the study of micropaleontological assemblages that could improve our understanding of the chronostratigraphic and paleoenvironmental characteristics of these rocks. In this study, we analyzed two cores of one of the thickest Cenozoic stratigraphic sections in the Caribbean region, from the ANH-TIERRALTA-2-X-P stratigraphic well, using palynomorphs and calcareous nannofossils. Our analysis allowed us to determine the age of deposition and understand the biostratigraphic patterns of marine and terrestrial microfossils in these nearshore deposits. We found that the first cored interval, from 2122 m to 2026.9 m, corresponds to marine rocks accumulated between the middle and late Eocene. The second interval, from 1130 m to 731.6 m, showed patterns of terrestrial and marine microfossils, which indicate the middle-late Eocene to the Early Miocene age. Palynological and calcareous nannofossil biostratigraphy were consistent in the middle to upper Eocene and Lower Miocene deposits, but discrepancies were observed in the Oligocene deposits. We attributed this to reworking or broader biostratigraphic ranges of certain palynological markers used in the biozones. Determining the age of the middle to upper Eocene and upper Eocene to lower Oligocene deposits was challenging due to the limited number of well-calibrated biostratigraphic markers. As a result, accurate correlation with the late Eocene – early Oligocene stratigraphic record from other parts of the SSJB is hindered, demonstrating that regional stratigraphic correlations based on biostratigraphy alone are problematic.

New material of heteromorph ammonites from the Lower Cretaceous of Lhozhag County, southern Tibet and its biostratigraphic implications

Cretaceous ammonites are still poorly known in Tibet, western China. Here we describe a new heteromorph ammonite fauna from the Lower Member of the Lakang Formation in the Lhozhag County, southern Tibet. Material of at least five genera are recognized, including Aspinoceras, ? Hemihoplites, Heteroceratidae gen. et sp. indet, ? Mortoniceras and Parancyloceras, among which three genera are reported from this area for the first time. This ammonite fauna indicates that the age of the Lakang Formation is approximately late Hauterivian to Albian (Early Cretaceous). This study proves that the Lakang Formation was not contemporaneous with the adjacent Gamba Group, which is slightly younger, different from a previous interpretation.

First record of late Devonian-early Carboniferous palynoflora from the Lipak Formation, Spiti Basin, Tethyan Himalaya, India, and their biostratigraphic implications

The present work elucidates palynofloral records from the Lipak Formation (late Devonian– early Carboniferous) of the Spiti Basin. The study has been carried out from three different sections of Spiti and Pin valleys to look for the signatures of terrestrial plants in the Tethyan realm and assess the relative palynodating of the studied sediments. The recovered palynoassemblage from the exposures of Lipak Formation, near Takche Locality, Spiti Valley, mainly comprises spores and has the dominance of Verrucosisporites, Dictyotriletes, Lophozonotriletes, Convolutispora followed by subordinate occurrences of Rugospora, Cymbosporites and Knoxisporites along with reworked pollen grain Plicatipollenites. The recovered palynoassemblage of Lipak Formation exposure at Guling Village of Pin Valley comprises Spelaeotriletes, Tricidarisporites, Calamospora, Callumispora and reworked pollen grains. The reworked pollen grains are characterised by the dominance of Faunipollenites, Scheuringipollenites and Parasaccites and followed by subordinate occurrences of the Densipollenites, Striatopodocarpites, Platysaccus, Alisporites, Striomonosaccites, Chordasporites and Verticipollenites pollen grains. The exposure of this Formation near Muth Village of Pin Valley is found to be palynologically barren. The recovered palynoflora is correlated with palynofloral records of the Tethyan realm of India and palynofloral records from coeval sequences worldwide. The recovered palynocomposition shows a close resemblance to Retispora lepidophyta–Verrucosisporites nitidus (LN) and Vallatisporites verrucosus–Retusotriletes incohatus (VI) Assemblage zones of Western Europe and Cordylosporites–Verrucosisporites Biozone of Argentina which indicates that studied section of the Lipak Formation is upper Famennian to early Tournaisian age. The recovered reworked palynomorphs belong to the Permian age, which may be deposited in the Lipak Formation through stratigraphic leakage. Palynomorphs include spores of affinities of Zygopteridiales, Marattiales, Botryopteridales, Equisetales/Noeggerathiales/Sphenophyllales group of plants. In contrast, palaeobotanical affinities of pollen grains are linked with the Filicales, Cordaitales and Glossopteridales group of plants.

NEW INSIGHT INTO THE MIDDLE EOCENE CALCAREOUS NANNOPLANKTON BIOSTRATIGRAPHY AND PALEOENVIRONMENT FROM FAYOUM AND BENI SUEF AREAS, EGYPT

The present study deals with calcareous nannoplankton paleoenvironmental and biostratigraphic implications as well as the genesis and the stratigraphic significance of an event bed recognized from the middle Eocene Beni Suef Formation in the sections of Gebel Na’alun (Fayoum area) and Gebel Homret Shaibun (Beni Suef area), Egypt. Calcareous nannoplankton biostratigraphy indicates that the Beni Suef Formation in the two areas is synchronous, covering an interval that may be correlated with the calcareous nannoplankton Zone NP17. Paleoenvironmental implications from calcareous nannoplankton suggests deposition of sediments in the Beni Suef Formation under relatively stable, temperate and mesotrophic conditions, with a short interval of eutrophication in the basal part of the Homret Shaibun section.

Calcareous nannofossils across the Eocene-Oligocene transition at Site 756 (Ninetyeast Ridge, Indian Ocean): implications for biostratigraphy and paleoceanographic clues

Calcareous nannofossils across the Eocene-Oligocene transition at Site 756 (Ninetyeast Ridge, Indian Ocean): implications for biostratigraphy and paleoceanographic clues

Middle Cenozoic micromammals from Linxia Basin, Gansu Province, China, and their implications for biostratigraphy and palaeoecology

We report late Oligocene to late Pliocene micromammal assemblages from 19 localities of the Linxia Basin of Gansu Province, China. Abundant material (> 7000 specimens) includes members of Eulipotyphla, Chiroptera, Rodentia and Lagomorpha, and comprises 121 species arranged in 24 families. The Yagou assemblage (basal part of the Jiaozigou Formation) is one of the few early Late Oligocene micromammalian faunas known from China. The Galijia (Dongxiang Formation) and Yihachi (“Liushu” Formation) assemblages represent the richest and most productive middle and late Miocene micromammal faunas known from northwestern China. These middle Cenozoic faunas show a closely similar community structure and taxonomic composition, and a similar pattern of faunal turnover, with contemporary faunas throughout the Mongol-Xinjiang Region, implying the existence of a unified biogeographic zone. The discoveries contribute to the temporal ordering of individual fossil assemblages of northern China and help develop a framework for Cenozoic biostratigraphy and biochronology in central Asia. Our palaeoenvironmental analysis suggests change towards warmer and moister equable habitats of the late Oligocene to early and middle Miocene, followed by the onset of drier temperate shrub-steppe environments. The composition of extant families of micromammals that developed during the Neogene reflects a faunal distribution analogous to the Holarctic Region today and suggests a shared ecology.

The last record of the last typotherid (Notoungulata, Mesotheriidae, Mesotherium cristatum) for the middle Pleistocene of the western Pampean region, Córdoba Province, Argentina, and its biostratigraphic implications

We document a new Last Appearance Datum of the mesotheriine notoungulate Mesotherium cristatum in 220 ± 13 ka, Middle Pleistocene of the west Pampean Region of the Province of Cordoba, Corralito, Santa María Department, Argentina. We increase the previous LAD of this taxon into ca. 530 ka compared to its latest occurrence in Ensenadan Age (ca. 1.95–0.4 Ma; Early-Middle Pleistocene) sediments from the east Pampean Region.Our detailed literature review of the traditional biostratigraphic support (“Mesotherium cristatum Biozone”) of the Ensenadan Age for the east Pampean Region, and our new temporal record of M. cristatum for the western region of the Pampean Region, .allows us to draw the following conclusions that affect the biostratigraphic model considered so far extensive in South America: (1) M. cristatum should no longer be considered as the guide taxon of the Ensenadan Age; (2) “M. cristatum Biozone” no longer constitutes the biostratigraphic support of the Ensenadan Age as it is also present in sediments of Bonaerian Age; (3) Distinct biostratigraphic units (“M. cristatum Biozone” and “Megatherium americanum Biozone”) overlap in their temporal ranges. In application of the International Stratography Code, we proclaim that the models of chronostratigraphic and biostratigraphic units, established for the Pampean Region, need a strong and consolidated biostratigraphic support, whose temporal limits must be defined by the presence of fossils and not by the temporal limits of the chronostratigraphic units.This study proclaims the biostratigraphic importance of the western Pampean Region near the Sierras Pampeanas (Córdoba Province) which due to its differential paleoecological conditions and its altitudinal diferenciation with respect to the eastern regions of the Pampean Region could have acted as a faunal reservoir during the Pleistocene.

New data on the Miocene vertebrate assemblage of the Zaysan Basin (Central Asia) with implications for biostratigraphy, paleoecology, and paleobiogeography

ABSTRACT The Zaysan Basin in Central Asia has a long geological history, and it has therefore seen major climatic and evolutionary transformations. The Miocene fossil record of this locality is remarkably rich representing all groups of vertebrates. A revision of fish remains has been carried out and new records of fishes, reptiles, and mammals recovered from Miocene deposits of the Zaysan Basin have been described. The study of fossils has revealed the existence of a quite diverse vertebrate assemblage in the basin during the Miocene. Representatives of the Percidae and Amiinae, and the species †Leobergia zaissanica predominated among fishes, whereas reptiles were supposedly represented in the assemblage by pan-trionychid turtles and crocodiles. No amphibians have been revealed, while the only mammalian taxa in the studied sample is a fossorial rodent of the genus †Tachyoryctoides. In contrast to previous views regarding the Middle Miocene age of the Zaysan Formation, the analysis of fish and mammal remains recovered from this locality strongly suggests an Early Miocene age. Findings of bowfin remains in the Zaysan Basin confirm that this group had existed outside of North America beyond the Paleogene/Neogene transition, and, at the same time, these specimens are the last known occurrences of the taxa Amiidae, Amiiformes, and Halecomorphi outside of North America. Data also indicate the existence of a lacustrine ecosystem in the Zaysan Basin during the Miocene with a taxonomically rich vertebrate assemblage and diverse trophic relations being an important center of biodiversity in the Miocene of Central Asia.

The ‘grooved’ Hildoceras ammonite fauna from the Lower Jurassic (Toarcian) of the Apennines. Overview and proposal for a new species

ABSTRACT It is historically renown that morphotypes referred to Hildoceras bifrons from the Apennines (Italy) and other Mediterranean localities differ in many ways from the typical species of the Central and North-West Europe. Besides overall smaller size (usually < 40 mm), Mediterranean specimens attain marked whorl embracement, comparable to that of the kin species Hildoceras semipolitum (albeit retaining a less compressed whorl section). Relatively larger (and rare) morphotypes may show slight 'uncoiling' (resembling the typical Hildoceras bifrons), though limitedly to the final part of the adult-stage last whorl. Both the common (small-involute) and rare (larger-slightly uncoiled) morphotypes thus reveal of ambiguous taxonomic attribution either as Hildoceras bifrons or as Hildoceras semipolitum. In front of this ambiguity, the new species Hildoceras appenninicus sp. nov. is proposed for grouping 'bifrons-like' Hildoceras occurring in the Apennines and other Mediterranean localities. In contrast with previous works on this subject, definite ranges for whorl compression indexes relative to whorl diameter and embracement are provided, by this attempting at a more objective distinction of this new species from both Hildoceras bifrons and Hildoceras semipolitum. Finally, along with some biostratigraphic remarks, possible evolutionary and paleobiogeographic implications concerning the arising and spreading of Hildoceras species are outlined. lsid: zoobank.org:pub:5C2C159E-61CA-4EE0-996D-D098618B3790

Revision ofHistiodella labiosaBauer, 2010, and its inferred phylogeny in the evolution of the Middle Ordovician conodont genusHistiodellaHarris, 1962

AbstractBased on abundant topotype specimens from the Oil Creek Formation at the type locality in southern Oklahoma,Histiodella labiosais described and revised. The morphological variation of the Pa, Pb, and M elements of this previously little-known species is also systematically documented and illustrated. The revised species definition, with formal designation of a lectotype and a new diagnosis supported by morphological comparison with its ancestral and descendent species, has enhanced its value for correlation of the lower Darriwilian. The inferred phylogeny ofHistiodellathat resulted from this study is based on both cladistic and morphological analyses. It supports the monophyletic grouping ofHistiodellaspecies and their evolutionary relationships. This has wide biostratigraphic implications because manyHistiodellaspecies are valuable for detailed global correlation of upper Dapingian to middle Darriwilian strata.

New occurrences of massetognathine traversodontids and chiniquodontids (Synapsida, Cynodontia) from the early Late Triassic Santacruzodon Assemblage Zone (Santa Maria Supersequence, southern Brazil): Geographic and biostratigraphic implications

We describe the fossil content of the Carolina Soil outcrop in Vera Cruz Municipality (Rio Grande do Sul State, Brazil), which represents one of the few localities with a conspicuous fossil record in the still poorly sampled Upper Triassic Santacruzodon Assemblage Zone (Santa Cruz Sequence, Santa Maria Supersequence). The site has yielded numerous specimens of the massetognathine traversodontid Santacruzodon hopsoni (Cynodontia: Gomphodontia) with a broad range of ontogenetic stages, and a new record of the chiniquodontid cynodont Chiniquodon sp. (Cynodontia: Probainognathia). The new material improves our knowledge of the anatomy of Santacruzodon, which is based on relatively incomplete, small-sized specimens collected in the Schöenstatt outcrop (Santa Cruz do Sul Municipality). Although Chiniquodon co-occurs with Santacruzodon in the Schöenstatt outcrop, its presence is not biostratigraphically significant, as Chiniquodon has a large biochron and geographical distribution, and its phylogenetic distribution requires to be comprehensively explored. However, this chiniquodontid is poorly represented in this Assemblage Zone, in contrast with the older Dinodontosaurus Assemblage Zone. The traversodontid Santacruzodon remains an index taxon of the Santacruzodon Assemblage Zone and aspects of the knowledge of its anatomy are here improved. The Carolina Soil outcrop represents one of the few fossiliferous localities known for this AZ, which was only briefly mentioned in previous studies and has a great paleontological potential for future studies.