Patagonian Localities Research Articles

Phylogenetic Implications of Dental Characters in Henricosborniidae (Mammalia, Notoungulata)

Henricosborniids are a group of South American native ungulates mainly found in Argentina (several Patagonian localities, Jujuy, and Mendoza), Brazil (São José de Itaboraí), and Bolivia (Tiupampa) that have a biochron ranging from the Danian (Tiupampan SALMA) to the late Bartonian (Barrancan subage of the Casamayoran SALMA). The record of henricosborniids in Mustersan levels must be confirmed. The family includes the genera Henricosbornia, Peripantostylops, Othnielmarshia, Orome, and Simpsonotus. Their fragmentary fossil record, mainly limited to isolated teeth, has constrained their utility for obtaining phylogenetically useful characters; for that reason, only few taxa (i.e., Henricosbornia, Simpsonotus) are usually included in this type of analysis. Even though there is consensus about the basal position of the group within the order, the family is recovered as polyphyletic or, more commonly, paraphyletic. The analysis of specimens from the early Eocene of Las Violetas and Las Flores (Itaboraian SALMA), the oldest Patagonian localities yielding notoungulate remains, and Paso del Sapo, along with the implementation of both implied weighting and landmark information, allow us to discuss several features for use in henricosborniid phylogenetic analysis and identification: 1) ectoloph of the molars with well-marked paracone and metacone folds; 2) molars with crochet present, oblique to the ectoloph, with variable development; 3) triangular third upper molar, with poorly developed hypocone; 4) reduced trigonid with short paralophid; 5) entoconid more like an isolated cusp and not completely crested. Although useful, these characters need to be evaluated in a more exhaustive phylogenetic context.

REVISION OF THE MIOCENE CAVIOMORPH RODENTS FROM THE RÍO SANTA CRUZ (ARGENTINEAN PATAGONIA)

Fossil rodents from the Río Santa Cruz (RSC) classic localities (Santa Cruz Formation, Early–Middle Miocene) are known by the works of F. Ameghino and W.B. Scott since the end of the 19th and beginning of the 20th centuries. These caviomorph rodents have not been comprehensively reviewed since then. In this contribution, we studied new fossil specimens from the cliffs of the RSC (Province of Santa Cruz, Argentina) collected with accurate stratigraphic and geographic data during fieldtrips in 2013 and 2014. An increase in the caviomorph taxonomic richness is observed, based upon our taxonomic study of caviomorphs previously recorded in the RSC. Also, these fieldworks recovered for the first time several taxa previously found in other Santacrucian and even older Patagonian localities (Colhuehuapian, Early Miocene). As a general evolutionary pattern, we note an increase of derived euhypsodont taxa (Prolagostomus, Pliolagostomus, Schistomys, and Eocardia) in Segundas Barrancas Blancas (16.47–15.3 Ma). In addition, a taxonomic replacement of Phanomys by Schistomys is noted between Barrancas Blancas (17.21–16.3 Ma) and Segundas Barrancas Blancas, as well as a notably increase in the abundance of the large Perimys onustus in the latter locality. The present study provides a revision of the caviomorph systematics, and intends to be the starting point to understand the diversity (in all its aspects) and the evolution of this group during the Santacrucian, a major event in the South American mammalian history.

Melting and metasomatism/refertilisation processes in the Patagonian sub-continental lithospheric mantle: A review

The large amount of geochemical variability in peridotitic and pyroxenitic xenoliths exhumed by Eocene to present-day magmas in Patagonia provides a unique opportunity to investigate the depletion and enrichment processes affecting the lithosphere in proximity of subduction settings and their relationships with magmatism. In this study, a review of the geochemical features of the Patagonian ultramafic xenoliths coupled with new SrNd isotopic data on clinopyroxene separates from representative suites enabled us to delineate the main melt extraction and enrichment (metasomatism vs. refertilisation) processes acting in these sub-continental lithospheric mantle (SCLM) portions. Our findings show that clinopyroxenes and orthopyroxenes in Patagonian harzburgites/lherzolites lie on two discrete Al2O3/Mg# trends and record variable partial melting degrees (1–30%), progressively decreasing southward, where the mantle domains experienced melt extraction in the past. The occurrence of both negative and positive correlations between (La/Yb)N, SrN, and Al2O3 in clinopyroxenes suggests that large part of the SCLM beneath Patagonia was affected by both metasomatic (low melt-fluid/rock ratio) and refertilisation (high melt-fluid/rock ratio or long-lasting low melt-fluid/rock interaction) processes, while a few portions - particularly in Southern Patagonia - were devoid of significant enrichment processes. A comprehensive study of the major/trace element composition and rare earth element patterns of clinopyroxene from both cumulitic and mantle xenoliths led us to hypothesize that tholeiitic enrichment was followed by infiltration of transitional/alkaline agents in the Northern and Central Patagonian SCLM. The percolation of melts with transitional affinity can be identified in some Central Patagonian localities. In Southern Patagonia clinopyroxenes record a slight interaction with alkaline and proto-adakitic agents; the latter occurred at Cerro Fraile, the locality nearest the trench. The SrNd xenolith isotopic signature led to speculation that enriched and depleted mantle components interacted variably in the SCLM domain beneath Patagonia. This work suggests that a detailed and comprehensive study of ultramafic xenoliths can help identify the evidence produced by magmatic events occurring at the surface, as both a serial affinity and a temporal sequence.

The Pre-Oligocene Diversity of Hypsodont Typotherians (Mammalia, Notoungulata) in Northwestern Argentina

Until the discovery of the genus Punahyrax (Geste Formation) in different localities of Catamarca and Salta provinces, “archaeohyracids” were unknown in northwestern Argentina. Here we analyze the record of these notoungulates in the region through specimens known for the Geste Formation and new remains recovered from the lower levels of the Quebrada de Los Colorados Formation, assessing their diversity and significance in the context of the pre-Deseadan radiation of Typotheria. We identify three “archaeohyracid” morphotypes for Barrancan levels and four for Mustersan levels in northwestern Argentina, implying the possible presence of as much as seven “archaeohyracid” taxa in the region for the last third of the Eocene, and illustrating a striking diversity, especially considering the scarce pre-Tinguirirican record known until now. These new records underline the faunal differences of the Geste and Quebrada de los Colorados formations regarding the highly fossiliferous Lower and Upper Lumbrera formations. In this sense, although the existence of a sample bias should not be completely dismissed, the possibility of important biogeographic barriers acting in the area by the late middle Eocene needs to be analyzed with independent evidence. The record of Pseudhyrax eutrachytheroides in northwestern Argentina represents the first notoungulate taxon common between this region and typical Patagonian localities and represents a useful and presumably reliable new basis for the assignment of a Mustersan age for the middle section of the Geste Formation

New Fossil Discoveries from the Miocene Santa Cruz Formation of Argentina

The Miocene Santa Cruz Formation of Patagonian Argentina yields well preserved skeletons of many groups of mammals, notably platyrrhine primates and sloths – groups known today from only tropical/subtropical environments and occupying purely arboreal niches. The classic high latitude (51 degrees South) Patagonian localities of this formation have been worked by many paleontologists for more than a century. Our project shifts the emphasis from the classical localities of the Lower Member (ELCm) to the comparatively less studied Upper Member (ELAm) farther south. The ELAm was originally reconstructed as a cooler, drier, and more open‐woodland environment. This paleoecological reconstruction is at odds with recent radiometric dates placing the Mid Miocene Climatic Optimum within the ELAm; the new dates imply that the ELAm was generally warmer and wetter than the ELCm. Our recent field expedition focused on three known localities of the ELAm. One of these (Monte Tigre) yielded abundant mammalian remains, including a diverse assemblage of sloths some of which appear to have been semi‐arboreal. There we also collected the first plant macrofossils known from the ELAm (mostly Nothofagus leaf impressions). Another locality (Cañadon Palos) yielded abundant small mammal remains, including the rare marsupial Abderites. The third locality (Cabo Buen Tiempo) yielded sporadic small mammal fossils (mainly rodents and small armadillos) from a tuffaceous sediment. Future work at these localities will include 1. stratigraphic correlation across 25 kilometers of beach cliffs and shelf, 2. continued fossil collecting at the known ELAm localities, 3. prospecting for new ELAm localities, and 4. paleobiological comparisons between ELAm and ELCm mammals focusing on primates and sloths. New fossils from other vertebrate groups and plant remains will permit a richer paleoecological reconstruction of the ELAm than was previously possible.Support or Funding InformationGenerous support for this study was provided by an American Association of Anatomists Fellows Grant to J. Perry.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Sabellid worms from the Patagonian Shelf and Humboldt Current System (Annelida, Sabellidae): Phyllis Knight-Jones’ and José María Orensanz’s collections

The South American sabellid polychaete worm collections of Phyllis Knight-Jones and José María Orensanz were recovered, curated and specimens identified, comprising fourteen species grouped in nine genera. Five species belonging to the genera Chone Krøyer, 1856, Acromegalomma Gil and Nishi, 2017, Notaulax Tauber, 1879, Parasabella Bush, 1905, and Pseudopotamilla Bush, 1905, are described as new to science from the Patagonian Shelf (Argentina). Jasmineira crumenifera Hartmann-Schröder, 1986, Myxicola sulcata Ehlers, 1912, Parasabella columbi (Kinberg, 1867), Perkinsiana antarctica (Kinberg, 1867) and Perkinsiana assimilis (McIntosh, 1885) are redescribed and reported from several Patagonian localities. Three new combinations are made: Sabella tilosaula Schmarda, 1861, is transferred to Notaulax, Sabella magalhaensis Kinberg, 1867, to Perkinsiana Knight-Jones, 1983, and Potamilla platensis Hartman, 1953, to Pseudopotamilla. Potamethus littoralis Hartman, 1967, was synonymized with Perkinsiana magalhaensis. Notaulax tilosaula, Perkinsiana antarctica and P. magalhaensis are reported from the biogeographical subregion Humboldt Current System, whereas Bispira sp., Chone orensanzi sp. nov., Jasmineira crumenifera, Acromegalomma schwindtae sp. nov., M. sulcata, Notaulax salazari sp. nov., Parasabella columbi, P. yonowae sp. nov., Perkinsiana assimilis, Pseudopotamilla platensis, and P. knightjonesae sp. nov., are reported from the Patagonian Shelf.

On the existence of non‐microbiotherian Australidelphian marsupials (Diprotodontia) in the Eocene of Patagonia

AbstractA diverse assemblage of extinct mammals of early–middle Eocene age (Ypresian–Lutetian boundary) come from the Patagonian localities of La Barda and Laguna Fría around Paso del Sapo in northwestern Chubut Province (Argentina). Metatherians are well represented, mostly by dental remains of ‘Didelphimorphia’, Paucituberculata, Sparassodonta, Microbiotheria, and Polydolopimorphia. Here we analyse three calcanea and one astragalus referable to the same, indeterminate taxon, from La Barda, showing the fusion of their ectal and sustentacular facets. This facet arrangement characterizes the Australidelphia, a marsupial clade represented by Microbiotheria from South America and Antarctica, plus all Australasian lineages. Other australidelphian features shown by these tarsals include: in the calcanea, a reduced peroneal process and a tripartite cuboid facet; in the astragalus, a round, very small astragalar head in relation to the body; a convex trochlea with a half for the tibia and half, in slightly lower position, for the fibula. Their size and other anatomical features suggest that the new tarsals cannot be referred to the Microbiotheria. Phylogenetic analysis suggests that the La Barda taxon lies within the Australidelphia, and that it is either closely related or belongs to, the Diprotodontia. The existence of advanced australidelphians in Patagonia adds further evidence of the close relationship between Patagonia, Antarctica, and Australia during the Late Cretaceous – early Palaeogene.

A new Leontiniidae (Notoungulata) from the Late Oligocene beds of Mendoza Province, Argentina

The present paper deals with the leontiniid remains recovered from the Late Oligocene (Deseadan) levels of Quebrada Fiera, Mendoza Province, central-western Argentina. The material consists of an almost complete skull associated with 11 vertebrae, as well as some maxillary and mandibular fragments and postcranial elements of different individuals, enabling a life reconstruction. The comparative study allows morphological differences with respect to other Deseadan taxa to be established, such as Scarrittia, Leontinia, Ancylocoelus, Anayatherium and Elmerriggsia, leading to the proposal of the new taxon Gualta cuyana gen. et sp. nov. The new genus and species is close to Scarrittia canquelensis in having upper I1 more developed than I2–3, mainly by its greater crown-height, and the canine overlapping the P1; it differs from this species by the longer, narrower nasals, longer rostrum, I2 not reduced, P3–4 with shallow lingual sulcus, shorter cervical vertebrae, and shorter calcaneum, lacking navicular facet. The complete dentition and/or the larger I1 differentiate Gualta cuyana from Leontinia, Ancylocoelus and Anayatherium ekecoa, as well as from the Miocene Colpodon. The lingual sulcus on P3–4 is much shallower than in Scarrittia barranquensis, Leontinia, Anayatherium and Elmerriggsia. The phylogenetic analysis shows poorly resolved relationships among leontiniids; when using equal weights, the analysis shows that Gualta cuyana is more related to the species of Anayatherium and Scarrittia canquelensis, whereas under implied weights, the new taxon is basal to other Palaeogene taxa. Gualta cuyana adds to other endemic taxa of the peculiar Deseadan assemblage from Quebrada Fiera. The new leontiniid constitutes a low percentage of fossil mammals within the Quebrada Fiera fauna, as is also true for this family in Salla (Bolivia), but in contrast with some Patagonian localities or the Brazilian Tremembé Formation where leontiniids are the best-represented mammal group.http://zoobank.org/urn:lsid:zoobank.org:pub:17749C84-4028-4FC8-A140-E1A6FE02466D

First Record of Mesotheriidae in the Late Oligocene of Mendoza Province, Argentina

The present paper deals with the description of the first remains of the Family Mesotheriidae in the Quebrada Fiera locality. The fauna from Quebrada Fiera comes from sediments nowadays considered to represent the base of the Agua de la Piedra Formation. The recovered faunal assemblage includes typical elements of the Deseadan Age (late Oligocene), shared with both Patagonian and lower latitude associations (e.g., Salla, Bolivia). A unique specimen of Mesotheriidae has been recovered after several field seasons since 2006. It is a palatal portion in two fragments, one bearing the I1 and the other with left P4-M2 and right M1-2. Morfological and metrical features of this material reveal a taxon much closer to the Patagonian mesotheriid species Trachytherus spegazzinianus than to the Bolivian taxa, T. alloxus and T. subandinus, and it is determined as Trachytherus cf. T. spegazzinianus. Its presence in Mendoza fills a gap in the expected geographical distribution of this mesotheriid, as it was also recorded in the Bolivian site of Lacayani. The scanty record of mesotheriids in Quebrada Fiera contrasts with Salla and Patagonian localities.

New Middle Miocene Caviomorph Rodents from Quebrada Honda, Bolivia

The rodents of the middle Miocene fauna of Quebrada Honda Bolivia are described. The most abundant rodent is the chinchillid Prolagostomus sp. More precise identification of this species will require revision of early to middle Miocene lagostomines, taking into account variation in modern populations. The next most common rodents are the tiny octodontoid Acarechimys, sp. nov.?, and the caviid Guiomys unica. The Acarechimys species may be unique to Quebrada Honda, but verification awaits revision of this geographically and temporally widespread genus. Guiomys unica is a recently described species otherwise known only from two Patagonian localities, El Petiso and Rio Chico. Two rodents are unique to Quebrada Honda. Mesoprocta hypsodus, gen. et sp. nov., is a dasyproctid distinguished by its very hypsodont, cement-covered cheek teeth. Quebradahondomys potosiensis, gen. et sp. nov., is an adelphomyine echimyid distinguished by the less oblique lophids of its trilophodont cheek teeth, among other features. The rodents of Quebrada Honda are more similar to those of Patagonia than those of northern South America, paralleling patterns seen in other mammal groups from this fauna.

The Beginning of the Age of Mammals in South America, Part III

The great cliff (Gran Barranca) south of Lago ColhueHuapi in southern Chubut, Argentina exposes nearly 25million years of sediments, from about 40 mya to18 mya. Gaps exist in this record, of course, and someintervals are more fossiliferous than others, but GranBarranca has been—and continues to be—one of themost important fossil localities in South America. It alsowas formative in the career of one of paleontology’sgreat thinkers: George Gaylord Simpson. Simpson madetwo expeditions to collect fossils at Gran Barranca andother Patagonian localities, and he later published twomassive and enduring works on mammals from GranBarranca and other Paleogene localities: The beginningof the age of mammals in South America, Parts I and II(Simpson 1948, 1967). The Paleontology of GranBarranca, edited by Richard Madden and a team ofcollaborators, follows in the tradition of Simpson in itsgoal of synthesizing knowledge of this important localityand what it indicates about the development of mammalfaunas in South America.This book is an edited volume of 29 chapters intendedfor an academic audience. Forty-five experts contributed asauthors or co-authors. The production quality of the volumeis excellent overall, and references are included at the endof each chapter rather than as a single section at the end ofthe book. There is a comprehensive taxonomic index,which I found to be very handy.The opening chapter introduces the reader to GranBarranca and the history of its discovery and exploration.It is a thoroughly researched historical narrative and one ofthe most enjoyable chapters in the book. It also offers novelinsights into who might have discovered this importantlocality.Part I, Geology, includes three chapters that addressthe physical stratigraphy, magnetostratigraphy, and geo-chronology of Gran Barranca. They together provide adetailed description of the geological and chronologicalcontexts of Gran Barranca. Seven faunal levels areidentified. Most of these faunal levels correspond topreviously recognized South American Land Mammal“Ages,” but two new intervals are noted: one betweenlevels pertaining to the Tinguirirican and DeseadanSALMAs and the other at the top of the sequence,above levels referable to the Colhuehuapian SALMA.The recognition of a post-Tinguirirican, pre-Deseadaninterval is intriguing and suggests that not all faunaspreviously considered to be Deseadan in age may in factpertain to the late Oligocene. The new absolute ageestimates provided for this and other intervals at GranBarranca provide extremely useful new data that willfacilitate both inter- and intracontinental correlations.Part II, Systematic Paleontology, includes a dozenchapters of varying scope, mostly focusing on mammals.Some chapters review and revise a restricted taxonomicgroup over the entire span of the Gran Barranca sequence.Others discuss a broader taxonomic group over a morerestricted temporal interval. A few are quite circumscribedand center on a single species or group from one faunalinterval. Many new genera and species are described, and

Odonatan endophytic oviposition from the Eocene of Patagonia: The ichnogenusPaleoovoidusand implications for behavioral stasis

We document evidence of endophytic oviposition on fossil compression/impression leaves from the early Eocene Laguna del Hunco and middle Eocene Rio Pichileufu floras of Patagonia, Argentina. Based on distinctive morphologies and damage patterns of elongate, ovoid, lens-, or teardrop-shaped scars in the leaves, we assign this insect damage to the ichnogenus Paleoovoidus, consisting of an existing ichnospecies,P. rectus, and two new ichnospecies,P. arcuatumandP. bifurcatus. InP. rectus, the scars are characteristically arranged in linear rows along the midvein; inP. bifurcatus, scars are distributed in double rows along the midvein and parallel to secondary veins; and inP. arcuatum, scars are deployed in rectilinear and arcuate rows. In some cases, the narrow, angulate end of individual scars bear a darkened region encompassing a circular hole or similar feature indicating ovipositor tissue penetration. A comparison to the structure and surface pattern of modern ovipositional damage on dicotyledonous leaves suggests considerable similarity to certain zygopteran Odonata. Specifically, members of the Lestidae probably producedP. rectusandP. bifurcatus, whereas species of Coenagrionidae were responsible forP. arcuatum. Both Patagonian localities represent an elevated diversity of potential fern, gymnosperm, and especially angiosperm hosts, the targets of all observed oviposition. However, we did not detect targeting of particular plant families. Our results indicate behavioral stasis for the three ovipositional patterns for at least 50 million years. Nevertheless, synonymy of these oviposition patterns with mid-Mesozoic ichnospecies indicates older origins for these distinctive modes of oviposition.

Macrofaunal assemblages associated with coralline turf: species turnover and changes in structure at different spatial scales

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 363:147-156 (2008) - DOI: https://doi.org/10.3354/meps07449 Macrofaunal assemblages associated with coralline turf: species turnover and changes in structure at different spatial scales María G. Liuzzi, Juan López Gappa* Museo Argentino de Ciencias Naturales, Av. Angel Gallardo 470, Buenos Aires C1405DJR, Argentina *Corresponding author. Email: lgappa@mail.retina.ar ABSTRACT: Our aim was to analyse changes in species turnover and structure of macrofaunal assemblages associated with intertidal coralline algal turfs at 4 spatial scales along the coast of Argentina (southwestern Atlantic): provinces (~106 m), localities (~104 m), sites (~102 m) and replicate quadrats (~1 to 3 m). Corallina officinalis was by far the dominant algal species in most samples, but C. elongata and Jania rubens var. rubens were also frequent. Frond density was 3 times higher in the southern, cold-temperate Chubut province than in the northern, warm-temperate Buenos Aires province. Macrofaunal species richness, diversity and evenness were also significantly higher in samples from Chubut than in those from Buenos Aires, with ‘province’ explaining 86 to 98% of the variance in the analytical model. In total, 118 macrofaunal taxa belonging to 11 invertebrate phyla were found. Mytilid bivalves and polychaetes were the most important groups contributing to differences between provinces. Brachidontes rodriguezii was extremely abundant in Buenos Aires province, while Rhynchospio glutaea and Perumytilus purpuratus were dominant in samples from Chubut. Changes in assemblage structure were significant at the scale of provinces, localities and sites in Patagonian localities. Measures of beta diversity showed that taxonomic turnover was correlated with distance between samples at scales of 104 m or higher, with the highest at the scale of provinces. Higher biodiversity in the Magellan assemblage than in warmer areas of the northern coast of Argentina may be related to the Pacific origin of the Magellan fauna, which entered the southwestern Atlantic during the Tertiary period. KEY WORDS: Coralline turf · Beta diversity · Latitudinal trends of biodiversity · Spatial scales · Rocky intertidal · Corallina · Argentina Full text in pdf format PreviousNextCite this article as: Liuzzi MG, López Gappa J (2008) Macrofaunal assemblages associated with coralline turf: species turnover and changes in structure at different spatial scales. Mar Ecol Prog Ser 363:147-156. https://doi.org/10.3354/meps07449 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 363. Online publication date: July 15, 2008 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2008 Inter-Research.

Late Oligocene mesotheriids (Mammalia, Notoungulata) from Salla and Lacayani (Bolivia): implications for basal mesotheriid phylogeny and distribution

The oldest known mesotheriids are referred to the genus Trachytherus, a taxon traditionally included in its own subfamily ‘Trachytheriinae’. The ontogeny, morphological variation and systematics of the genus Trachytherus are still poorly understood and the monophyly of this taxon is questionable. For the first time, a large collection of basal mesotheriids (belonging to the genus Trachytherus) yielded by the Bolivian Salla beds (Deseadan, late Oligocene) and previously referred to T. spegazzinianus was included in a large-scale analysis. This has led to the recognition of a unique new species in the locality of Salla-Luribay, distinct from T. spegazzinianus: Trachytherus alloxus sp. nov. Skulls of this species are described and cheekteeth variation range throughout ontogeny is discussed. These new data are incorporated in a parsimony analysis of basal mesotheriids. The most probable hypothesis of a clade T. spegazzinianus-mesotheriines is discussed. The distinction of the new Salla species from the Patagonian species T. spegazzinianus confirms the faunal differences observed between these Bolivian and Patagonian Deseadan localities. Moreover, the assignment to Trachytherus spegazzinianus of mesotheriid remains from the Bolivian Lacayani deposits complicates the problem of these faunal differences. Further systematic investigations on the Lacayani fauna and on the age of the Patagonian localities are needed. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 152, 153–200.

Oldest world Chelidae (Chelonii, Pleurodira), from the Cretaceous of Patagonia, Argentina

Four new taxa are described. Three of them are attributed to the extant Phrynops group: a primitive member, unidentified within the group or related to the large extant Phrynops forms; a primitive member of the Acanthochelys subgroup, small extant members of the group; a more evolved member, although still primitive, of the large extant Phrynops . The fourth is either a representative of an extinct group or a form related to the extant Chelus group. The presence of the second taxon in older Patagonian localities, as early as Lower Albian, indicates that the diversification of the extant groups was achieved as early as the Lower Cretaceous. Quatre nouveaux taxons sont créés. Trois sont attribués au groupe Phrynops : un membre primitif ou apparenté aux grands Phrynops actuels ; un membre primitif du sous-groupe des petits Acanthochelys ; un plus récent, plus évolué vers les grands Phrynops actuels. Le quatrième est, soit un représentant d'une lignée indépendante éteinte, soit un membre apparenté au groupe Chelus . La présence du second, Prochelidella n. g., dans d'autres localités de Patagonie, dès l'Albien inférieur notamment, atteste que la diversification des groupes actuels est réalisée à cette date et remonte probablement au moins à la base du Crétacé.

The oldest and first nearly complete skeleton of a chelid, of the Hydromedusa sub-group (Chelidae, Pleurodira), from the Upper Cretaceous of Patagonia

Abstract A new pleurodiran (side necked) turtle is described on material from the Upper Cretaceous of Patagonia, from sediments outcropping at Cerro Blanco, Yaminue Creek, Rio Negro, Argentina. The sediments are compared to those from the Pellegrini lake area referred to the middle Member of the Allen Formation, Upper Campanian-Lower Maastrichtian. Yaminuechelys gasparinii n.g., n.sp., is a pleurodiran turtle on the pelvis sutured to the shell and a chelid on the formula of cervical vertebrae and the lateral cheek emargination, deeply extended towards (as here) or up to the posterior emargination. It is the oldest record of a nearly complete skeleton of a chelid, long necked (elongated cervical vertebrae, lowered skull), and the first sufficiently known of the Chelodina-Hydromedusa group (elongated skull, lowered neural arch and centrum of the cervicals, low zygapophyses processes, strong polygoned decoration) and of the Hydromedusa sub-group (widened inner nares by reduced palatine ossification). The carapace is 41,8 cm long. It is more primitive than Hydromedusa (Eocene-Extant, South America) and retains primitive characters either still present or no more present in the other chelids of the Pseudemydura, Emydura and Phrynops groups (short necked) and Chelus group (long necked), representing the anterior clades of phyletic diversification [Gaffney, 1977], or evolutive grades, of the family. Such are plesiomorphic, relative to Hydromedusa, the less pronounced lateral skull emargination, wider and longer hyoid elements, wider nucal and cervical, this not drawn back, presence of lateral mesoplastra, not shortened bridge, straight borders of the not shortened and not widened posterior plastral lobe, amphicoelous sacrals and caudal vertebrae uniting amphicoelous, concavoplaty--(i.e. anteriorly concave, posteriorly flat) and procoelous or weakly procoelous elements. As Hydromedusa, Yaminuechelys n. g. retains primitive characters such as the long series of neurals, the very lateral attachment of the axillar and inguinal processes and the attachment of the pelvis, below pleural 8 (and 7 in the extant form) and a small part of the suprapygal, and the ischitatic sutures prolonged on the xiphiplastral points. It is distinguished by the apomorphic presence of a wide and week anterior carapacial notch. Yaminuechelys n.g., or aff. Yaminuechelys spp. are known in Patagonia by fragmentary remains in a dozen of Upper Cretaceous and two Palaeocene localities. Before them, chelids are known in the world only by undefined smaller forms from Lower Albian and Upper Albian-Cenomanian Patagonian localities. In Australia, they are known from Palaeocene-Lower Eocene (no Cretaceous data before) with already extant Australian diversified forms. Yaminuechelys n.g. demonstrates how long the diversification in chelids is realized in South Gondwana before the full break of the continents.

Omphalodiella Patagonica, A New Peltate Lichen Genus And Species From South America

AbstractOmphalodiella patagonica Henssen gen. et sp. nov. is described from two Patagonian localities in Argentina. In habit the new lichen resembles some species of Acarospora in having brown, peltate thalli less than 3 mm wide with immersed apothecia. The ontogeny and structure of the apothecia and pycnidia correspond, however, to genera of the Parmeliaceae. The apothecia are provided with a meristematic, cupular exciple, and the amyloid asci contain 8 or less, ± globose spores. The short-celled conidiophores produce rod-shaped conidia of bayonet type. The thallus is provided with a narrow paraplectenchymatic upper and a broad prosoplectenchymatic, strongly gelatinized lower cortex. The thallus contains gyrophoric acid; the cortex contains ‘glomellifera brown ’.