Revision of the Proteaceae macrofossil record from Patagonia, Argentina

Proteaceae are restricted to the Southern Hemisphere, and of the seven tribes of the subfamily Grevilleoideae, only three (Macadamieae, Oriteae, and Embothrieae) have living members in Argentina. Megafossil genera of Proteaceae recorded from Patagonia includeLomatia, Embothrium, Orites, andRoupala. In this report, we evaluate and revise fossil Argentine Proteaceae on the basis of type material and new specimens. The new collections come from the Tufolitas Laguna del Hunco (early Eocene, Chubut Province), the Ventana (middle Eocene, Río Negro Province), and the Río Ñirihuau (late Oligocene-early Miocene, Río Negro Province) formations, Patagonia, Argentina. We confirm the presence ofLomatia preferruginea Berry,L. occidentalis (Berry) Frenguelli,L. patagonica Frenguelli,Roupala patagonica Durango de Cabrera et Romero, andOrites bivascularis Romero, Dibbern et Gandolfo. Fossils assigned toEmbothrium precoccineum Berry andE. pregrandiflorum Berry are doubtful, and new material is necessary to confirm the presence of this genus in the fossil record of Patagonia. A putative new fossil species of Proteaceae is presented as Proteaceae gen. et sp. indet. Fossil Proteaceae are compared with modern genera, and an identification key for the fossil leaf species is presented. Doubtful historical records of Proteaceae fossils for the Antarctic Peninsula region and Patagonia are also discussed. Based on this revision, the three tribes of Proteaceae found today in Argentina were already present in Patagonia by the early Eocene, where they probably arrived via the Australia-Antarctica-South America connection.     

New Glyptodont from the Codore Formation (Pliocene), Falcón State, Venezuela, its relationship with theAsterostemma problem, and the paleobiogeography of the Glyptodontinae

One of the basal Glyptodontidae groups is represented by the Propalaehoplophorinae (late Oligocene — middle Miocene), whose genera (Propalaehoplophorus, Eucinepeltus, Metopotoxus, Cochlops, andAsterostemma) were initially recognized in Argentinian Patagonia. Among these,Asterostemma was characterized by its wide latitudinal distribution, ranging from southernmost (Patagonia) to northernmost (Colombia, Venezuela) South America. However, the generic assignation of the Miocene species from Colombia and Venezuela (A.? acostae, A. gigantea, andA. venezolensis) was contested by some authors, who explicitly accepted the possibility that these species could correspond to a new genus, different from those recognized in southern areas. A new comparative study of taxa from Argentinian Patagonia, Colombia and Venezuela (together with the recognition of a new genus and species for the Pliocene of the latter country) indicates that the species in northern South America are not Propalaehoplophorinae, but represent the first stages in the cladogenesis of the Glyptodontinae glyptodontids, the history of which was heretofore restricted to the late Miocene — early Holocene of southernmost South America. Accordingly, we propose the recognition of the new genusBoreostemma for the species from northern South America and the restriction ofAsterostemma to the Miocene of Patagonia. Thus, the available data indicate that the Glyptodontinae would in fact have arisen in the northernmost regions of this continent. Their arrival to more southerly areas coincides with the acme of the “Age of Southern Plains”. The Propalaehoplophorinae are geographically restricted to Patagonia.     

A new chinchilloid (Rodentia,Hystricognathi) from the early Miocene of the localities of Bryn Gwyn and Gran Barranca (Patagonia,Argentina)

A new genus and species of chinchilloid rodent is described here. It was found in Colhuehuapian levels (early Miocene) of the localities of Bryn Gwyn and Gran Barranca, Chubut Province, Argentina. The new taxon shows a unique combination of characters (e.g., protohypsodont teeth, upper molars trilophodont, m1 and m2 tri- or tetralophodont with the second crest in position of variable development, and m3 trilophodont, cement absent) that make it different from any other known chinchilloids. We performed a phylogenetic analysis to corroborate the relationships of the new taxon within the Chinchilloidea. Our results indicate that the new taxon is best classified as Chinchilloidea incertae sedis, together with Incamys, Garridomys, and Scotamys. These species form the basal stock that leads to the modern lineage Chinchillidae (chinchillas and viscachas). The presence of the new taxon in these localities increases the diversity of chinchilloids during the early Miocene and reduces the dissimilarity between the faunas found in Bryn Gwyn and Gran Barranca.     

A New Glyptodont (Xenarthra: Cingulata) from the Late Miocene of Argentina: New Clues About the Oldest Extra-Patagonian Radiation in Southern South America

Glyptodonts (Xenarthra, Cingulata) are one of the most amazing Cenozoic South American mammals, with some terminal forms reaching ca. two tons. The Paleogene record of glyptodonts is still poorly known, although some of their diversification is observable in Patagonian Argentina. Since the early and middle Miocene (ca. 19–13 Ma), two large clades can be recognized in South America. One probably has a northern origin (Glyptodontinae), while the other one, called the “austral clade”, is interpreted to have had an austral origin, with the oldest records represented by the “Propalaehoplophorinae” from the late early Miocene of Patagonian Argentina. In this scenario, the extra-Patagonian radiations are still poorly known, despite their importance for understanding the late Miocene and Pliocene diversity. Here, we carry out a comprehensive revision of late Miocene (Chasicoan Stage/Age) glyptodonts of central Argentina (Buenos Aires and San Juan provinces). Our results show that, contrary to what is traditionally assumed, it was a period of very low diversity, with only one species recognized in this region, Kelenkura castroi gen et sp. nov. Our phylogenetic analysis shows that this species represents the sister taxon of the remaining species of the “austral clade”, representing the first branch of the extra-Patagonian radiation. Additionally, K. castroi is the first taxon showing a “fully modern” morphology of the caudal tube.

     

New anhingid (Aves,Suliformes) from the middle Miocene of Río Negro province,Patagonia, Argentina

During the Miocene in South America, the family Anhingidae constitutes one of the most conspicuous faunal elements. However, the anhingid record from Patagonia is still sparse. The aim of the present contribution is to describe a new species of Macranhinga coming from Colloncuran levels (early middle Miocene) in Río Negro province, north-central Patagonia (Argentina). The new species is represented by an incomplete proximal end of a tarsometatarsus, distal end of a tibiotarsus, and distal end of a humerus. The phylogenetic relationships of the new species within Macranhinga remains unresolved. South American Neogene anhingids share a number of features that suggest they may belong to a monophyletic clade within this family. Anhingid records from the Miocene of Patagonia indicate that the diversity of this family was far more diverse (at least 4 different species) than currently understood, and was possible comparable to that shown by Miocene beds of Mesopotamian in Argentina and Acre in Brazil.

http://www.zoobang.org/urn:lsid:zoobank.org:pub:3FC228E8-4E2C-4DFD-AB91-79F32269CA98     

First Evidence for Wollemi Pine-type Pollen (Dilwynites: Araucariaceae) in South America

We report the first fossil pollen from South America of the lineage that includes the recently discovered, extremely rare Australian Wollemi Pine, Wollemia nobilis (Araucariaceae). The grains are from the late Paleocene to early middle Eocene Ligorio Márquez Formation of Santa Cruz, Patagonia, Argentina, and are assigned to Dilwynites, the fossil pollen type that closely resembles the pollen of modern Wollemia and some species of its Australasian sister genus, Agathis. Dilwynites was formerly known only from Australia, New Zealand, and East Antarctica. The Patagonian Dilwynites occurs with several taxa of Podocarpaceae and a diverse range of cryptogams and angiosperms, but not Nothofagus. The fossils greatly extend the known geographic range of Dilwynites and provide important new evidence for the Antarctic region as an early Paleogene portal for biotic interchange between Australasia and South America.     

The southernmost record of a Neuryurini Hoffstetter, 1958 (Mammalia,Xenarthra, Glyptodontidae)

In this contribution we document the southernmost and probably the oldest record of the tribe Neuryurini (Glyptodontidae). The southernmost record of this tribe outside of Patagonia is Neuryurus sp. from Lujanian sediments (Luján Formation, late Pleistocene–early Holocene) at Quequén Grande River (Buenos Aires Province, Argentina). The first and only previous record of a specimen of the Neuryurini in Patagonia was reported from the upper levels of the Puerto Madryn Formation (Huayquerian SALMA, late Miocene), exposed in Península Valdés (Chubut Province, Argentina). The new specimen described here and assigned to an indeterminate Neuryurini was recovered at Estancia La Peninsular (Santa Cruz Province, Argentina). This locality has been recognized in geological studies as part of the Santa Cruz Formation (Santacrucian SALMA, late early Miocene), but there have been no fossils described from this site until now. Therefore, the new specimen represents, with the two confirmed records of Glyptodon Owen and Panochthus Burmeister (both from the Quaternary), the only non-Propalaehoplophorinae glyptodontids reported for Santa Cruz Province.     

A review of Semigenetta (Viverridae,Carnivora) from the Miocene of Eurasia based on material from the hominid locality of Hammerschmiede (Germany)

The present article offers a detailed review of the taxonomy, distribution and palaeoecology of the genus Semigenetta. The study is based on new craniodental and postcranial remains of the genus from the early late Miocene (Tortonian) locality of Hammerschmiede (Bavaria, Germany). Most of the new specimens are attributed to the medium-sized species Semigenetta sansaniensis, whereas one lower carnassial is assigned to the large-sized Semigenetta grandis, making Hammerschmiede 4 the first known locality with two species of the genus. The variability of the material of S. sansaniensis from Europe allows us to revise the taxonomic weight of some previously used characters, and to identify the smaller-sized late Miocene form Semigenetta ripolli as a junior synonym of the former. Such an evolutionary transition of S. sansaniensis towards smaller forms is explained by niche partitioning with larger carnivorans of similar ecology, such as the herein reported S. grandis. Additionally, the species Semigenetta huaiheensis is here considered as a junior synonym of Semigenetta elegans.     

A new Miocene fauna of snakes from eastern Siberia,Russia.: Was the snake fauna largely homogenous in Eurasia during the Miocene?

Togay, a locality from Ol’khon Island, Baykal Lake, Russia, has yielded a fauna of snakes of Late Middle or early Late Miocene age. It is located in a broad area from which no Neogene snake has been reported; therefore, it represents an important landmark. The fauna includes a non-erycine boid, two or three colubrids, a viperid of the ‘oriental complex’ of Vipera, and perhaps another viperid. This assemblage is astonishingly reminiscent of the snake faunas from the late Early and early Middle Miocene from western and central Europe, it being understood that Miocene faunas are practically unknown in the geographically intermediary area. It may be entertained whether a homogenous snake fauna inhabited Eurasia (except the southern part of the continent) during the Miocene.     

Systematics and evolutionary significance of the small Abrocomidae from the early Miocene of southern South America

Octodontoidea is the most species-rich clade among hystricomorph rodents, and has a fossil record going back to at least the late Oligocene. Affinities of fossils previous to the late Miocene differentiation of the extant families Abrocomidae, Echimyidae and Octodontidae are controversial, essentially because these fossils may share few apomorphies with modern species. In fact, pre-late Miocene representatives of Abrocomidae had not been recognised until very recently. Here we revise the early Miocene genus Acarechimys, originally assigned to Echimyidae, and alternatively to stem Octodontoidea or to Octodontidae. A systematic and parsimony-based phylogenetic analysis of the species traditionally included in Acarechimys showed that this genus is part of stem Abrocomidae. These results are primarily supported by morphology of the mandible and lower molars. Acarechimys is here restricted to three species, A. minutus, A. pulchellus and Acarechimys pascuali sp. nov., while another species, A. constans, is here transferred to a new abrocomid genus. The remaining species were nested within Octodontidae. According to these results, Abrocomidae might have been as diverse as its sister clade Octodontidae-Echimyidae during the late Oligocene–early Miocene. Extinction of this diversity would have resulted in marked loss of evolutionary history, with extant abrocomids being currently restricted to late-diverged euhypsodont representatives.     

A Peculiar New Pampatheriidae (Mammalia: Xenarthra: Cingulata) from the Pleistocene of Argentina and Comments on Pampatheriidae Diversity

Pampatheriidae are a group of cingulates native to South American that are known from the middle Miocene to the lower Holocene. Two genera have been recognized between the lower Pleistocene and the lower Holocene: Pampatherium Gervais and Ameghino (Ensenadan, Bonaerian and Lujanian, lower Pleistocene–lower Holocene) and Holmesina Simpson (Blancan, Irvingtonian, upper Pliocene–lower Holocene). They have been mainly differentiated by their osteoderm morphology and cranio-dental characters. These taxa had a wide latitudinal distribution, extending from the southern part of South America (Península Valdés, Argentina) to North America (Florida, USA). In this contribution, we describe a new genus and species of Pampatheriidae for the lower and middle Pleistocene of Buenos Aires Province and for the upper Pleistocene of Santa Fe Province (Argentina).The new taxon is represented by disarticulated osteoderms, one skull element, two thoracic vertebrae and a right femur and patella. It has extremely complex osteoderm ornamentations and particular morphological characters of the cranial element and femur that are not found in any other species of the family. This new taxon, recorded in the lower–middle Pleistocene (Ensenadan Stage/Age) and in the upper Pleistocene–early Holocene (Lujanian Stage/Age), is incorporated to the Pleistocene mammal assemblage of South America. Finally, the Pampatheriidae diversity is greater during the Lujanian Stage/Age than the Ensenadan Stage/Age.     

A New Late Miocene Odobenid (Mammalia: Carnivora) from Hokkaido,Japan Suggests Rapid Diversification of Basal Miocene Odobenids

The modern walrus, Odobenus rosmarus, is specialized and only extant member of the family Odobenidae. They were much more diversified in the past, and at least 16 genera and 20 species of fossil walruses have been known. Although their diversity increased in the late Miocene and Pliocene (around 8–2 Million years ago), older records are poorly known. A new genus and species of archaic odobenid, Archaeodobenus akamatsui, gen. et sp. nov. from the late Miocene (ca. 10.0–9.5 Ma) top of the Ichibangawa Formation, Hokkaido, northern Japan, suggests rapid diversification of basal Miocene walruses. Archaeodobenus akamatsui is the contemporaneous Pseudotaria muramotoi from the same formation, but they are distinguishable from each other in size and shape of the occipital condyle, foramen magnum and mastoid process of the cranium, and other postcranial features. Based on our phylogenetic analysis, A. akamatsui might have split from P. muramotoi at the late Miocene in the western North Pacific. This rapid diversification of the archaic odobenids occurred with a combination of marine regression and transgression, which provided geological isolation among the common ancestors of extinct odobenids.     

A New Early Miocene Chinchilloid Hystricognath Rodent; an Approach to the Understanding of the Early Chinchillid Dental Evolution

Chinchilloidea is an emblematical group of caviomorph rodents characterized by euhypsodont, laminated cheek teeth. Recent molecular analyses proposed that the extant Dinomys (and implicitly its fossil allies) is also part of this group. Their relationships with fossil caviomorphs with less derived dental features are still obscured by the deficiency of the fossil record documenting its early dental evolution. The new genus and species Garridomys curunuquem, from the early Miocene deposits of the Cerro Bandera Formation, northern Patagonia, is here described. It is represented by numerous mandible and maxillary remains with dentition. This species has protohypsodont cheek teeth with three transverse crests in all ontogenetic stages arranged in a transitory S-shaped pattern, resembling putative early dinomyids. Garridomys curunuquem is here interpreted as the sister group of the clade including the living and fossil chinchillids; both chinchillas and viscaccias would have diverged from a Garridomys-like ancestor and acquired hypsodonty independently. Garridomys and other chinchilloids would have diverged from the lineage leading to chinchillids in pre-Oligocene times, suggesting a very early, still poorly documented chinchilloid radiation.     

First identification of Decennatherium Crusafont, 1952 (Mammalia,Ruminantia, Pecora) in the Siwaliks of Pakistan

Previously undescribed remains of a new large giraffid have been identified from the late Miocene Siwaliks Hills of the Potwar Plateau in Pakistan. This taxon is very intimately related to the late Miocene giraffid genus Decennatherium, previously only certainly identified in the Iberian Peninsula, and with some possible remains assigned to Decennatherium crusafonti from Aliäbäd (Iran). The new material collected in the Siwaliks Hills shows a high morphological similarity with the Spanish remains of the genus, especially the early Vallesian Decennatherium pachecoi. Two previously undescribed ossicone fragments from the same area are also described and identified as cf. Decennatherium. These findings represent the easternmost occurrence of the genus Decennatherium and show a late Miocene migration of the genus throughout the Iberian Peninsula and Southern Asia.     

Dabbling ducks (Aves: Anatidae) from the Middle Miocene of Mongolia

A new genus and two new species of ducks (Aves: Anatidae) from the Middle Miocene Sharga locality are described. Mioquerquedula minutissima gen. et sp. nov. is a very small duck. Anas velox Milne-Edwards, 1868 from the Middle Miocene of France is transferred to the genus Mioquerquedula. Aix praeclara sp. nov. described here is the oldest record of the modern genus Aix. A revision of the previously described small duck Anas soporata Kurochkin, 1976 shows that only the specimens from the Sharga locality should be referred to this species. The status of other small ducks from the Neogene of Europe and North America is discussed. The diversity of herbivorous and diving ducks in the Sharga locality indicates that Miocene Shargyn Govi Lake was rich in food resources.     

The youngest South American rhynchocephalian,a survivor of the K/Pg extinction

Rhynchocephalian lepidosaurs, though once widespread worldwide, are represented today only by the tuatara (Sphenodon) of New Zealand. After their apparent early Cretaceous extinction in Laurasia, they survived in southern continents. In South America, they are represented by different lineages of Late Cretaceous eupropalinal forms until their disappearance by the Cretaceous/Palaeogene (K/Pg) boundary. We describe here the only unambiguous Palaeogene rhynchocephalian from South America; this new taxon is a younger species of the otherwise Late Cretaceous genus Kawasphenodon. Phylogenetic analysis confirms the allocation of the genus to the clade Opisthodontia. The new form from the Palaeogene of Central Patagonia is much smaller than Kawasphenodon expectatus from the Late Cretaceous of Northern Patagonia. The new species shows that at least one group of rhynchocephalians not related to the extant Sphenodon survived in South America beyond the K/Pg extinction event. Furthermore, it adds to other trans-K/Pg ectotherm tetrapod taxa, suggesting that the end-Cretaceous extinction affected Patagonia more benignly than the Laurasian landmasses.     

<Emphasis Type="Italic">Gryposuchus</Emphasis> (Crocodylia,Gavialoidea) from the early Miocene of Venezuela

Here, a fragment of a mandible recently discovered in the Cerro Zamuro site (Castillo Formation, Lara State, northwestern Venezuela) is assigned to the giant gavialoid Gryposuchus. This specimen, recovered from putative brackish environments of the early Miocene (~18 Ma) age, is unequivocally the earliest record of the genus in South America. Gryposuchus, together with the other gryposuchine previously recognized from the Castillo Formation, Siquisiquesuchus venezuelensis, increases the early Miocene taxonomic diversity of the group in the northern Neotropics. This new information from the Castillo Formation supports the conclusion that early gryposuchine evolutionary stages were in coastal, shallow marine or brackish environments, while the presence of some genera, such as Gryposuchus, in middle to late Miocene freshwater environments, is secondary habitat colonization late in the evolution of the clade. Freshwater colonization is probably the result of the gradual adaptation of early marine-adapted gryposuchines to the extensive estuarine-like environments of northern South America lowlands associated with marine transgressions that systematically occurred during the middle Eocene to early Oligocene. This new record is evidence of the wide chronological distribution of Gryposuchus in northern South America, highlighting the importance of this area as the center of origin and radiation of this successful Miocene gavialoid.