Santa Cruz Province Research Articles

Endscrapers Variability and Differential Use of Landscapes During the Late Holocene in Central-Western Santa Cruz, Patagonia

ABSTRACT In the last 2500 years BP the environment of Southern Patagonia was affected by significant climatic changes. In this scenario, in the central-western portion of Santa Cruz province (Patagonia, Argentina), hunter-gatherer populations made a complementary use of the different ecological areas (highlands and lowlands). Differences in artefactual assemblages have been recorded in these areas. Within this context, we analyze variability in the most frequent lithic artifact from the region: endscrapers. We assess morphology and compare results between different sectors from highlands and lowlands. The question is whether the morphology of endscrapers also differs between ecological areas. Quantitative (length, width and thickness) and qualitative variables (raw material and blank type) were measured on 514 endscrapers. Results show that there are no statistical differences between highlands and lowlands. Variability in dimensions is only detected for some raw materials. Indeed, standardization in the morphology of this type of tool is proposed for the period under study.

Stand Characteristics, Leaf Traits and Growth of Threatened Conifer Pilgerodendron uviferum (Cupressaceae) in Southern Patagonia, Argentina

Pilgerodendron uviferum is an endemic Cupressaceae of Patagonia (Argentina) that is restricted to a small group of individual trees, growing in isolated populations (relicts) along its distribution. The main objective was to evaluate the habitat, forest structure, leaf traits, leaf nutrient reabsorption and growth of four relicts (area between 0.3 and 0.86 ha) in the Santa Cruz province (Argentina) to improve the available information for forest conservation purposes. Principal components analysis was conducted to determine the separation between relict populations based on their ecological characteristics (individual and habitat levels). We found contrasting environmental and forest structure conditions among the four studied relicts. For example, two relicts associated with Nothofagus antarctica showed higher values of P. uviferum tree density, DBH and dominant height at the stand level. Alongside that, these relicts presented a higher sapling density (1950–3167 ind ha−1) and understory plant diversity compared to pure P. uviferum relicts growing near the ecotone with the steppe grassland. Specific leaf area, carbon and nutrient concentrations in P. univerum leaves varied depending on the relict conditions and tree age of the individuals. The mean nutrient resorption efficiency varied according to relicts and particular nutrients, ranging from 18.1% to 49.5% for Ca and P, respectively. The diameter growth of the dominant P. univerum trees ranged from 0.33 to 0.46 mm yr−1, indicating that the species follows a stress-tolerant strategy. The information of this work may assist in the conservation of marginal P. uviferum forest communities spatially disconnected with continuous forests, growing in relicts.

Within the forest: a new species of Ctenomys (Rodentia: Ctenomyidae) from northwestern Patagonia

Abstract The genus Ctenomys is represented by 68 species within at least 9 species groups. In Patagonia, there are 11 described species of Ctenomys in 3 phylogenetic species groups: (1) the sociabilis group; (2) the magellanicus group; and (3) the mendocinus group—added to this is C. maulinus, which is not clearly related to any species group. The magellanicus group is the most representative of Patagonia and includes 6 species, several unnamed forms, and has a widespread distribution from Río Negro and Neuquén provinces in the north of Patagonia to Tierra del Fuego province to the south. The magellanicus group is a highly supported clade and comprises 3 geographically defined lineages: the bidaui clade (northern clade) composed of C. bidaui, C. pulcer, and several undescribed forms; the polytypic haigi clade (central clade) comprising C. haigi, C. contrerasi, C. thalesi, C. sericeus, and Ctenomys cf. C. lentulus (sensu Teta and D’Elía 2020); and the monotypic magellanicus clade (southern clade) consisting of haplotypes assigned to C. magellanicus (including C. colburni). Ctenomys magellanicus (Magellanic Tuco-tuco) is widely distributed from southern Santa Cruz province in Argentina and central Aysén in Chile to Isla Grande de Tierra del Fuego in Argentina and Chile. Based on mitochondrial Cytochrome b DNA sequences and morphological assessment (qualitative and quantitative), we describe a new species of Ctenomys related to C. magellanicus from northwestern Chubut Province, Argentina. We provide anatomical comparisons between the new species and other species of Ctenomys from Patagonia, especially C. magellanicus, C. haigi, and C. plebiscitum. In addition, we recognize 2 groupings within C. magellanicus because of their morphometric differences, and report new localities for C. haigi and C. plebiscitum.

Another Traveler Design In Southern Patagonia: Long Edges (Knives and Side-Scrapers) Manufactured on Bifacial Blanks

ABSTRACT New information is presented on the particular design of side-scrapers and knives, referred to as long-edge artifact on biface (LEAB), and its spatial and temporal distribution in southern Patagonia is explored. The analysis considers morphological and technological characteristics, the presence of four specific attributes (overshot, platform, end thinning, and domes), and functional information at a microscopic level. A total of 101 lithics originating from academic investigations, private collections, and environmental impact assessments from different locations around the Santa Cruz province (Patagonia, Argentina) are studied. The distribution of LEAB reaches different sectors of steppe and mountain forest areas from at least 7000 years BP and into the late Holocene. In addition, LEAB manufacture among inland hunting-gathering populations and between them and maritime hunter-gatherers is recorded. These results support the transmission of information about LEAB design circulation across Southern Patagonia.

Southernmost lepidosaur (Reptilia) assemblage from the Late Cretaceous of Patagonia

ABSTRACT The aim of the present contribution is to describe new materials of lepidosaur reptiles coming from the late Cretaceous (Maastrichtian) Chorrillo Formation, at Santa Cruz province, Argentina. The lepidosaur assemblage is composed by four different snakes (belonging to basal snakes, madtsoiids, and ‘anilioids’) and a tuatara sphenodont. The latter is a new genus and species represented by an incomplete maxilla that shows strong ties to extant Sphenodon. The snakes are represented by isolated vertebrae that indicate they belong to basal forms. Both are very apomorphic and in all probability are the representatives of poorly known lineages. In contrast with recent claims, the fact that most members of this lepidosaur assemblage are highly apomorphic may be indicative of some biogeographical isolation from other Cretaceous lepidosaur associations reported from northern Patagonia.

New records of Trichinella patagoniensis from Argentina

Trichinella spiralis was long considered the sole Trichinella species in Argentina. However, since 2004, various Trichinella species, including the encapsulated Trichinella patagoniensis and Trichinella britovi, as well as the unencapsulated Trichinella pseudospiralis, have been detected in the country. The present study aimed to identify Trichinella ML at the species level from cougars naturally infected from Argentina. To this end, muscle tissue samples from one cougar each from Córdoba, Neuquén, and Santa Cruz Provinces were individually analysed using the artificial digestion technique. DNA extraction and molecular identification of Trichinella species were conducted on individual muscle larvae by PCR amplification of the ESV region and subsequent PCR amplification and sequencing of the COI gene. Morphological analysis revealed muscle larvae with characteristics consistent with Trichinella genus. PCR revealed a single band of approximately 127 bp for each individual muscle larva. PCR amplification of the COI gene from each isolate generated a 309 bp band. Sequencing of the mitochondrial COI gene confirmed the identity of the parasite as T. patagoniensis. The present study documents new occurrences of T. patagoniensis in Puma concolor from Argentina, including the first detection of T. patagoniensis in Puma concolor from Córdoba and Neuquén Province. These findings expand the limited knowledge of T. patagoniensis distribution in Argentina.

Distribution, Nesting Records, and Notes on the Ecology of the White-Throated Caracara (Phalcoboenus albogularis)

ABSTRACT Endemic to Patagonia, the White-throated Caracara (Phalcoboenus albogularis) is one of the least studied caracara species, with several aspects of its ecology, such as breeding biology and diet, largely unexplored. Using citizen science records and opportunistic observations, we obtained data on the breeding biology, nest sites, and diet of the species in Chile and Argentina. Nests were in rocky outcrops and cliffs, and aspects of diet corroborated others’ observations that this species feeds on live prey as well as carrion. The species’ nesting season apparently begins in September and ends in March, with some regional variation. The modal brood size is two, and many nests apparently are used across multiple years. Using citizen science data, we created the first distribution models for the White-throated Caracara, one for the breeding season and one for the winter season. The species predominantly occupies the highland plateaus of western Santa Cruz Province, Argentina, and the Andes Range from around 40° south to southern Tierra del Fuego. The models indicate a mostly consistent distribution without significant latitudinal changes between seasons and, apparently, only a limited transition to lower-elevation areas east of the Andes in winter. In both seasons, this caracara is associated primarily with barren rocky areas and Andean and sub-Andean herbaceous steppe—all open environments—rather than forested areas as has been thought previously. This study provides new knowledge of this regional endemic yet the species remains a poorly known raptor in southern South America. Additional and on-the-ground field research would likely produce benefits when addressing species-related conservation issues.

Exploring the range of Culex mosquitoes in Western Argentinean Patagonia, unveiling the presence of Culex pipiens bioform pipiens in South America.

Culicids in Argentinean Patagonia are characterized by low species diversity and adaptation to extreme environmental conditions, yet few studies have been conducted in the region. To further assess the occurrence of Culicidae in Western Patagonia, and in particular the presence of Culex pipiens bioforms at the southernmost extent of their distribution, immature and adult specimens were collected aboveground across various land uses located in shrubland, steppe, and deciduous forest between 38.96 and 46.55°S. Mosquitoes were reported at 35 of the 105 inspected sites. Five species from the genus Culex were identified, all of which were present in the steppe and the forest, while only Cx. apicinus and members of the Cx. pipiens complex were collected in the shrubland. Within the latter, a total of 150 specimens were molecularly identified by PCR amplification of Ace-2 and CQ11 loci. The first-to-date occurrence of bioform pipiens in South America is reported, along with the first records of Cx. quinquefasciatus signatures in Patagonia. In addition, the distribution of Cx. acharistus and Cx. dolosus as south as Santa Cruz province is expanded, and the first record of Cx. eduardoi in Río Negro province is provided. Immature specimens of Cx. pipiens were conspicuous in human-made aquatic habitats (both containers and in the ground), while Cx. acharistus was more prominent in artificial containers and Cx. eduardoi was mainly in ground habitats, either natural or human-made. These findings provide valuable insights into the distribution and ecological roles of these mosquito species in a region of extreme environmental conditions.

Vegetation Type Mapping in Southern Patagonia and Its Relationship with Ecosystem Services, Soil Carbon Stock, and Biodiversity

Vegetation Type (VT) mapping using Optical Earth observation data is essential for the management and conservation of natural resources, as well as for the evaluation of the supply of provisioning ecosystem services (ESs), the maintenance of ecosystem functions, and the conservation of biodiversity in anthropized environments. The main objective of the present work was to determine the spatial patterns of VTs related to climatic, topographic, and spectral variables across Santa Cruz province (Southern Patagonia, Argentina) in order to improve our understanding of land use cover at the regional scale. Also, we examined the spatial relationship between VTs and potential biodiversity (PB), ESs, and soil organic content (SOC) across our study region. We sampled 59,285 sites sorted into 19 major categories of land cover with a reliable discrimination level from field measurements. We selected 31 potential predictive environmental dataset covariates, which represent key factors for the spatial distribution of land cover such as climate (four), topography (three), and spectral (24) factors. All covariate maps were generated or uploaded to the Google Earth Engine cloud-based computing platform for subsequent modeling. A total of 270,292 sampling points were used for validation of the obtained classification map. The main land cover area estimates extracted from the map at the regional level identified about 142,085 km2 of grasslands (representing 58.1% of the total area), 38,355 km2 of Mata Negra Matorral thicket (15.7%), and about 25,189 km2 of bare soil (10.3%). From validation, the Overall Accuracy and the Kappa coefficient values for the classification map were 90.40% and 0.87, respectively. Pure and mixed forests presented the maximum SOC (11.3–11.8 kg m−2), followed by peatlands (10.6 kg m−2) and deciduous Nothofagus forests (10.5 kg m−2). The potential biodiversity was higher in some shrublands (64.1% in Mata Verde shrublands and 63.7% in mixed shrublands) and was comparable to those values found for open deciduous forests (Nothofagus antarctica forest with 60.4%). The provision of ESs presented maximum values at pure evergreen forests (56.7%) and minimum values at some shrubland types (Mata Negra Matorral thicket and mixed shrubland) and steppe grasslands (29.7–30.9%). This study has provided an accurate land cover and VT map that provides crucial information for ecological studies, biodiversity conservation, vegetation management and restoration, and regional strategic decision-making.

Bow and arrow: Chronological and social context of the introduction of new technologies in Southern Patagonia

Research carried out in the western region of the Santa Cruz province (Patagonia, Argentina), indicates a widespread and simultaneous use of diverse weapons with different launching modes during the Late Holocene. Bow and arrow, spear and/or darts and boleadoras were used as part of adaptive strategies appropriate for a changing environmental context. We recently suggested a prevalence of bow and arrow towards the end of the Late Holocene. The aim of this work is to define a chronology that will allow us to discuss the causes behind the introduction of the bow and arrow and the time it was abandoned. A further goal is to discuss the existence of an immediate replacement of the previous weapons (spears and/or darts) for the bow and arrow. Several factors (social, environmental, ecological and technological) that could explain its beginning, permanence and discard will be analyzed. We are especially interested in emphasizing the short period of its presence in the region, established circa 800/900 BP till 1520 AD as documented by Pigafetta in his chronicle.This work includes the analysis of more than 400 lithic points recovered in different sites within the region. Some of these are related to absolute dates that have been compared with other chronologies of specific technologies from the Late Holocene.Results are discussed taking into consideration the profound changes that occurred in the organizational systems of hunter-gatherer societies during this period. These gave a functional significance to the bow and arrow and other technologies. We consider this work is a contribution to understand the role of new technologies in a changing social context. Thus, we present original data and essential discussion relevant for south American and global archaeological studies.

Angiosperm fossil woods from the Upper Cretaceous (Cardiel Formation) of Argentinean Patagonia

Abstract We describe nine angiosperm fossil woods from sediments of the Cardiel Formation (Upper Cretaceous) near the Cardiel Lake, Santa Cruz Province, Argentinian Patagonia. On the basis of the characteristics of the anatomy, the specimens were placed in three fossil species: Weinmannioxylon trichospermoides related to the Cunoniaceae, Burseroxylon panzai sp. nov. possibly related to the Anacardiaceae or Burseraceae, and a new taxon with unknown affinity, Tortorellixylon oligoporosum gen. et sp. nov. Angiosperms are 15% of the assemblage and conifers 85%, which is consistent with previous studies of fossil woods from the Late Cretaceous of Patagonia. Most specimens show poorly distinct growth ring boundaries that suggest a weakly marked annual seasonality during the deposition of the Cardiel Formation. In addition, the specimens’ size and the rings’ curvature are consistent with large trees. Decay patterns similar to those produced by modern xylophagous fungi are also recognized in most specimens. The identification of three species in an assemblage of nine fossil woods suggests a significant taxonomic richness of angiosperms, and the taxonomic composition suggests a Late Cretaceous age for the Cardiel Formation (probably Campanian–Maastrichtian). These new records allow a better understanding of the composition of the fossil forests of the Late Cretaceous of Patagonia, in which the tree canopy was apparently dominated by conifers.

Archangelskyoxylon carlquistii gen. et sp. nov. Taxonomy and phylogeny of an unequivocal gnetoid Jurassic fossil wood from Argentina

Archangelskyoxylon carlquistii gen. et sp. nov. is based on anatomical secondary xylem from the Lower Jurassic (Sinemurian–Toarcian) in the Roca Blanca Formation of Santa Cruz Province, Patagonia, Argentina. The woods are preserved as siliceous permineralization and examined by light and scanning electron microscopy. The new fossil wood shows a set of anatomical features of the secondary xylem (e.g., vessels with simple, scalariform, foraminate, and modified foraminate perforation plates; vessel with bordered pits with outer aperture vestured or non-vestured, and inner aperture vestured; tracheids with bordered pits; septate fiber-tracheids, and uni to biseriate parenchyma rays), that are related to the Gnetidae and closely resembles those of Gnetum. The new taxon was compared with existing Gnetidae species and included in a phylogenetic analysis to test its relationships with fossil and extant genera of Gnetidae. In the resulting phylogenetic hypothesis, Archangelskyoxylon is placed into a clade that is closely related to Weltwitschia and Gnetum. This finding supports the existence of this lineage in the south of Gondwana during the Jurassic and reinforces the hypothesis that lineages related to the Gnetaceae diverged earlier in South America.

Littoral meiofauna community structure in San Julián bay, Santa Cruz province, Argentina

For the first time, standing stocks and community structure have been reported in San Julián Bay, located in the Santa Cruz province, toward the southern tip of South America, within the sub-Antarctic region. The mean density of the meiofauna found was 6724 individuals/10 cm2, with a high dominance of nematodes (97.69%). Multivariate studies (PERMANOVA) revealed two distinct meiofauna assemblages: one, in an upper littoral salt marsh habitat and other, in a medium to low soft bare sediment. In the middle of the bay —in front of San Julián city— salt marsh habitats had the highest meiofaunal density, while bare sediments (medium-low levels) were the lowest. The mean average in the salt marsh area was 12246 individuals/10 cm2, with nematodes being dominant followed by oligochaetes as the subdominant taxa. The mean average in bare sediments (medium to low levels) was 3962 individuals/10 cm2, with nematodes as dominant and turbellarians, mastigophorans and maxillopodos (harpacticoid copepods) as subdominant taxa. Bare sediments related to Patagonian mussel’s populations presented the lowest meiofauna densities. Diversity showed an opposite trend, with a maximum in medium-low levels and a minimum in salt-marshes habitat. Richness in number of taxa ranged from 8 to 12, with a total number of 18 taxa. Despite dominance of nematodes in meiofauna assemblages is known, maximum density found in San Julián bay is much higher than previously found for estuaries from north and mid-latitudes littoral sandy beaches and in the nearby region of the Straits of Magellan and Beagle Channel and other sub-Antarctic and Antarctic sites. On the other hand, the number of meiofauna taxa (no nematodes) is low, and its community structure differs from what has been reported in previous studies. The meiofauna taxa assemblages provide evidence that, in salt-marsh habitats, they have the highest densities, but the lowest diversity when compared with lower levels. This is likely due to adaptation problems of meiofauna communities to a semi-terrestrial habitat.

Fossil vertebrates from the Cerro Fortaleza Formation (Upper Cretaceous), Santa Cruz Province, Argentina

The Cerro Fortaleza Formation is a stratigraphic unit that crops out near the Cerro Fortaleza hill, northwestern Santa Cruz province, Argentina. This unit has been well-known since the end of the XIX century, and because of the finding of abundant dinosaur bones, it was named as the “Capas con dinosaurios” (=Dinosaur Beds). Intensive work since the end of the 1990's resulted in the finding of diverse dinosaur species and other vertebrates. The fossil assemblage recovered includes lamniform sharks, lepisosteiforms, the dipnoan Atlantoceratodus iheringi, chelid turtles, peirosaurid crocodyliforms, mosasaur teeth, and diverse dinosaur remains. Dinosaurs include a partial tail of a small-sized titanosauriform, and another, identified as Dreadnoughtus, shows derived procoelous caudals. Isolated sauropod teeth indicate the presence of a derived lithostrotian and the enigmatic Clasmodosaurus spatula Ameghino, 1899. Among theropods, abelisaurid and megaraptorids are reported. A partial ulna, manual claw and metatarsal belonging to the holotype of the enigmatic theropod Austrocheirus isasii are also described. The morphology of the new elements does not comfortably fit with abelisaurid or megaraptorid theropods, and the affinities of Austrocheirus among theropods still remain elusive. The fossil vertebrate content of the Cerro Fortaleza Formation indicates close similarities with the faunistic assemblage previously reported from the Mata Amarilla Formation (Cenomanian-Turonian), and strong differences are present with the overlying Chorrillo Formation (Maastrichtian). This may indicate that some kind of change among terrestrial vertebrates occurred at the Campanian/Maastrichtian boundary in the Austral Patagonia Basin.

Triclabendazole resistance in Fasciola hepatica: First report in sheep from the Santa Cruz province, Argentinian Patagonia.

In the fall of 2022, decreased triclabendazole (TCBZ) efficacy against F. hepatica was suspected in a sheep farm located in the Santa Cruz province, Argentinian Patagonia. Since TCBZ-resistance in F. hepatica has never been reported in this province, this study aimed to confirm potential TCBZ-resistance in F. hepatica and to evaluate the efficacy of closantel (CLO) and nitroxinil (NTX), through faecal egg count reduction test (FECRT), and the efficacy of albendazole (ABZ) through the in vitro egg hatch test (EHT) in sheep. Sixty-eight (68) animals were selected from a herd of eighty (80) female Merino naturally infected with F. hepatica based on eggs per gram of F. hepatica (EPGFh) counts and assigned into four (4) groups (n=17 per group): Group Control, animals did not receive anthelmintic treatment; Group TCBZ, animals were orally treated with TCBZ (12mg/kg); Group CLO, animals were orally treated with CLO (10mg/kg); and Group NTX, animals were subcutaneously treated with NTX (10mg/kg). The fluke egg output was monitored on days 0 and 21 post-treatment. For the EHT, liver fluke eggs were isolated from faecal samples (approx. 50g) collected from animals of the control group. TCBZ efficacy against liver fluke was 53.4%, confirming the presence of TCBZ-resistant isolates on the farm. CLO and NTX were highly effective (100%) for the treatment of F. hepatica on this farm. The EHT was carried out in two different laboratories, in which was observed an ABZ efficacy of 95.8 (Bariloche) and 96.5% (Tandil). These results indicate the ABZ susceptibility of this F. hepatica isolate and the inter-laboratory precision of the test.

First AMS radiocarbon dating of Río Chico style paintings (southernmost Patagonia, Argentina): Older than expected

This paper presents the first AMS 14C dating of the Río Chico Style from southernmost Patagonia (52°S). These paintings are characterised by the dominance of geometric linear motifs and a low frequency of figurative ones. According to a few indirect radiocarbon dating of stratified pigments and the chronology of nearby sites, the Río Chico Style has traditionally been dated to ca. 2000 BP, although an earlier chronology (ca. 8000 BP) has also been proposed according to Fell Cave (Magallanes, Chile) stratigraphy. Here we present the first AMS 14C dating for this style from three rock paintings at Romario Barría Rockshelter (Pali Aike volcanic field, Santa Cruz province, Argentina). The main objectives of this work are, first, to discuss the chronology of the Río Chico style from direct and indirect datings, second, evaluate the use of the site according to painting manufacture, and finally, analyse the distribution of Río Chico style at the regional scale and its connections with other lines of evidence, such as lithic assemblages, to discuss the role of rock art in highly mobile southern Patagonia hunter-gatherer societies.

Novel B2 mitogenomes from Continental southern Patagonia's Late Holocene: New insights into the peopling of the Southern Cone.

The main aim of this study is to discuss the migratory processes and peopling dynamics that shaped the genetic variability of populations during the settlement of the Southern Cone, through the analysis of complete mitogenomes of individuals from southern Patagonia. Complete mitogenomes were sequenced through massively parallel sequencing from two late Holocene individuals (SAC 1-1-3 and SAC 1-1-4) buried in the same chenque at Salitroso Lake Basin (Santa Cruz province, Argentina). To evaluate matrilineal phylogenetic affinities with other haplotypes, maximum likelihood and Bayesian phylogenetic reconstructions were performed, as well as a haplotype median-joining network. The mitogenomes were assigned to haplogroups B2 and B2b, exhibiting an average depth of 54X and 89X (≥1X coverage of 98.6% and 100%), and a high number of nucleotide differences among them. The phylogenetic analyses showed a relatively close relationship between the haplotype found in SAC 1-1-4 and those retrieved from a Middle Holocene individual from Laguna Chica (Buenos Aires province), and from a group of individuals from the Peruvian coast. For the SAC 1-1-3, no clear affiliations to any other haplotype were established. The large divergence between the haplotypes presented in this study suggests either a highly variable founder gene pool, or a later enrichment by frequent biological contact with other populations. Our results underline the persistence of genetic signals related to the first waves of peopling in South America, suggesting that the regional settlement of the southern end of the continent has been much more complex than initially thought.

Triassic Equisetites lateralis Phillips with strobilus in organic connection from Patagonia of Argentina and endophytic oviposition insect scars

Equisetites lateralis Phillips (=Equisetum laterale (Phillips) Gould) (Equisetaceae) is recorded for the first time for the Triassic of Gondwana. The specimens come from the upper section of the Cañadón Largo Formation, late Ladinian–early Carnian, Santa Cruz Province, Argentina. The identification is based on sterile and fertile remains, preserved as stems, leaf sheaths, nodal diaphragms, and strobilus in organic connection. The first morphological and anatomical data of the epidermal cells and stomatal apparatus of Gondwanan Triassic Equisetites are presented. This species is characterized by having stems unbranched, 8–23–35 free leaves tips in the leaf sheaths, cart-wheel structure, internode and lower part of the leaf-sheath showing scattered sunken stomata and ovate terminal strobilus with whorls of peltate sporangiophores. Herein, we described the fine sculptures in the epidermal and subsidiary cells, as pilulae and thickenings of the outer walls surrounding the sunken stomata. The Patagonian specimens identified as E. lateralis display characters of both subgenus (Hippochaete and Equisetum) of extant Equisetum. The first record of oviposition scars tentatively assigned to Odonatoptera are described from Triassic of Argentina, and are identified as Paleoovoidus contactus. Oviposition scars and paleoenvironmental interpretation of the formation, suggest that these plants could have grown in shallow water of the local lacustrine/palustrine deposits.

Algal association and angiosperm diversification from the early Cretaceous (Springhill Formation) of Patagonia: Insights into palaeoclimate and aquatic environments at Río Correntoso locality, Argentina

Well-preserved and diverse Early Cretaceous palynological assemblages were studied from an outcrop section of the Springhill Formation at the Río Correntoso locality (PRC), close to Ghío Lake, in Santa Cruz Province, Patagonia, Argentina. The studied log corresponds to the northernmost outcrops known for the Springhill Formation in the Austral Basin. Most of the palynomorphs algae (Botryococcus, Sphaeroplea, Lecaniella, Zygnema, Pseudoschizaea, Schizosporis, Ovoidites), and some angiosperm pollen grains (Proxapertites, Longapertites, Arecipites) are distinctive and characterize the palaeoenvironment and palaeoclimate of PRC, which was dominated by estuarine coastal margin sedimentites deposited under warm and humid conditions. These angiosperm pollen grains correspond to the earliest record of these group in Patagonia, represented by diverse monosulcates and one rare tricolpate type. This new record of angiosperm pollen in the Springhill Formation provides further evidence that one of the earliest diversifications of angiosperms started at least during the early Cretaceous in Patagonia.Sergio Archangelsky provided an invaluable expertise in the field of paleobotany in multiple ways. His knowledge transcended not only through his papers but also through his exceptional oratory skills. His talks were always enriching in every aspect, combining an engaging historical account with a vision towards the future.“…La paleobotánica un placer, debe ser algo agradable, es decir uno cuando trabaja en paleobotánica le gusta lo que hace, y cuando uno está describiendo, uno se va, y es lo mismo que componer una pieza musical, te perdés, te perdés en todo y lo hacés con gusto, con pasión…” “…The paleobotany is a pleasure, it should be something enjoyable, meaning that when you work in paleobotany, you love what you do. And when you're describing, you get lost, just like composing a musical piece. You lose yourself, in everything, and you do it with pleasure, with passion…”.The file with the voice of Sergio Archangelsky is in Supplementary file under Sergio_Archangelsky.mp3.

Systematic revision of the species of Protypotherium (Notoungulata: Interatheriidae) from the Santa Cruz Formation (Early–Middle Miocene), Argentinian Patagonia: a new phylogenetic hypothesis for the Interatheriidae

Abstract Protypotherium is one of the main genera of the Interatheriidae due to its species richness, abundance, and wide distribution from southern to middle latitudes of Argentina, Bolivia, Uruguay, and Chile. This genus is better known from the species founded by Florentino Ameghino during late 19th century from the prolific Santa Cruz Formation (Santacrucian South American Land Mammal Age (SALMA); Burdigalian–Early Langhian), Santa Cruz Province (Argentina). This contribution provides the taxonomic revision of the Santacrucian species of Protypotherium and the species erected by Florentino within this genus. We conclude that among the initial 21 species, Protypotherium antiquum, Protypotherium australe, Protypotherium praerutilum, Protypotherium compressidens, and Protypotherium claudum are valid, whereas Protypotherium obstructum is a Hegetotheriidae indet. We present a phylogenetic analysis that does not recover Protypotherium as a clade, due to the nesting of Juchuysillu and Caenophilus, and this assemblage appears as the sister taxon of the clade Progaleopithecus plus Archaeophylus. Finally, the interatheriines from the Santa Cruz Formation do not allow a subdivision of this unit, due to their wide geographic and temporal distribution, thus rejecting the biozones preliminary proposed by other authors. The Atlantic coast (east) and Río Santa Cruz (central) regions are similar in their interatheriine content, but both differ from the western area.