Pub Date : 2021-06-30DOI: 10.5710/AMGH.07.01.2021.3400
A. D. Farjat
Abstract. Modiomorphid bivalves from the Silurian and Devonian beds of the Central Andean Basin of Western Gondwana are herein presented. This paper is not only a systematic updated revision of certain species of modiomorphids but also includes the description of newly found ones in Bolivia. They were collected from 17 scattered outcrops along Eastern Cordillera, Eastern Altiplano, Interandean, and Subandean regions of Bolivia. A total of 55 specimens, well- to regularly-preserved, were studied. The Sphenotomorpha orientalis new species from the Interandean of Mataral is described. The genus Sphenotomorpha is reported for the first time from Ludlowian layers of the Central Andean Basin with Sphenotomorpha sp. A. Other species described and systematically discussed are Modiomorpha concentrica, Modiomorpha cf. pimentana, Sphenotomorpha ulrichi and Sphenotomorpha cf. bodenbenderi? Forms classified as Modiomorphidae indet. A, B, and C are studied and some discussions about their previous and current taxonomic designations are herein presented. The biostratigraphic distribution of the two cosmopolitan genera, Sphenotomorpha, 1916, and Modiomorpha, 1869, is proposed. From the Eifelian to the Frasnian, endobyssal forms, such as Modiomorpha concentrica, coexisted with foot forms like Modiomorphidae indet. C and Sphenotomorpha sp. B, which would have developed a discreet byssus. This research contributes to the still inaccurately known Silurian and Devonian palaeogeography of the Central Andean Basin.
{"title":"Silurian and Devonian Modiomorphidae Bivalves from Bolivia","authors":"A. D. Farjat","doi":"10.5710/AMGH.07.01.2021.3400","DOIUrl":"https://doi.org/10.5710/AMGH.07.01.2021.3400","url":null,"abstract":"Abstract. Modiomorphid bivalves from the Silurian and Devonian beds of the Central Andean Basin of Western Gondwana are herein presented. This paper is not only a systematic updated revision of certain species of modiomorphids but also includes the description of newly found ones in Bolivia. They were collected from 17 scattered outcrops along Eastern Cordillera, Eastern Altiplano, Interandean, and Subandean regions of Bolivia. A total of 55 specimens, well- to regularly-preserved, were studied. The Sphenotomorpha orientalis new species from the Interandean of Mataral is described. The genus Sphenotomorpha is reported for the first time from Ludlowian layers of the Central Andean Basin with Sphenotomorpha sp. A. Other species described and systematically discussed are Modiomorpha concentrica, Modiomorpha cf. pimentana, Sphenotomorpha ulrichi and Sphenotomorpha cf. bodenbenderi? Forms classified as Modiomorphidae indet. A, B, and C are studied and some discussions about their previous and current taxonomic designations are herein presented. The biostratigraphic distribution of the two cosmopolitan genera, Sphenotomorpha, 1916, and Modiomorpha, 1869, is proposed. From the Eifelian to the Frasnian, endobyssal forms, such as Modiomorpha concentrica, coexisted with foot forms like Modiomorphidae indet. C and Sphenotomorpha sp. B, which would have developed a discreet byssus. This research contributes to the still inaccurately known Silurian and Devonian palaeogeography of the Central Andean Basin.","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":"58 1","pages":"242 - 271"},"PeriodicalIF":1.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46185850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-30DOI: 10.5710/AMGH.30.11.2020.3404
Aitziber Suárez-Bilbao, Naroa García-Ibaibarriaga, J. Ortiz, T. Torres, A. Arrizabalaga, M. Iriarte-Chiapusso, X. Murelaga
Abstract. Sites corresponding to Marine Isotope Stage MIS 5c and MIS 4 like Artazu VIII, with a continental record but no hominin imprints or carnivore activities, are very scarce in the Iberian Peninsula. The Artazu VIII cave fill (Arrasate, northern Spain) was discovered in 2013 and is presented here for the first time, including detailed stratigraphic and sedimentological descriptions of the differentiated 12 levels, as well as an ordered chronology of most levels, covering at least 36.000 years. In addition, the small mammal assemblage yielded a total of 8,129 identifiable skeletal remains corresponding to 14 taxa. The conditions inferred from the ecological preferences of the small mammal associations have been correlated with four different stages and substages from MIS 5c to MIS 4 in which the woodland mass expanded and retreated, depending on the relative temperature and humidity in each period. Finally, considering the species variability and estimated palaeoenvironment, a comparison with the NGRIP δ18O curve and other sites with the same chronology has been performed, showing that Artazu VIII is one of the few deposits attributable to the Marine Isotopic Stages previously mentioned and the only one that correlates to the Greenland Interstadial 18 from the Iberian Peninsula.
{"title":"Late Pleistocene Palaeoenvironmental Variations from Marine Isotope Stages 5 and 4: Small Mammals at Artazu VIII Site (Arrasate, Northern Iberian Peninsula)","authors":"Aitziber Suárez-Bilbao, Naroa García-Ibaibarriaga, J. Ortiz, T. Torres, A. Arrizabalaga, M. Iriarte-Chiapusso, X. Murelaga","doi":"10.5710/AMGH.30.11.2020.3404","DOIUrl":"https://doi.org/10.5710/AMGH.30.11.2020.3404","url":null,"abstract":"Abstract. Sites corresponding to Marine Isotope Stage MIS 5c and MIS 4 like Artazu VIII, with a continental record but no hominin imprints or carnivore activities, are very scarce in the Iberian Peninsula. The Artazu VIII cave fill (Arrasate, northern Spain) was discovered in 2013 and is presented here for the first time, including detailed stratigraphic and sedimentological descriptions of the differentiated 12 levels, as well as an ordered chronology of most levels, covering at least 36.000 years. In addition, the small mammal assemblage yielded a total of 8,129 identifiable skeletal remains corresponding to 14 taxa. The conditions inferred from the ecological preferences of the small mammal associations have been correlated with four different stages and substages from MIS 5c to MIS 4 in which the woodland mass expanded and retreated, depending on the relative temperature and humidity in each period. Finally, considering the species variability and estimated palaeoenvironment, a comparison with the NGRIP δ18O curve and other sites with the same chronology has been performed, showing that Artazu VIII is one of the few deposits attributable to the Marine Isotopic Stages previously mentioned and the only one that correlates to the Greenland Interstadial 18 from the Iberian Peninsula.","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":"58 1","pages":"223 - 241"},"PeriodicalIF":1.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43920296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-30DOI: 10.5710/AMGH.11.11.2020.3395
A. J. Sagasti, D. Guido, J. G. García Massini, K. Campbell
Abstract. Taphonomic studies were carried out at Laguna Flecha Negra locality (Bahía Laura Complex, Middle–Late Jurassic), Santa Cruz Province, Argentina. Sedimentary facies and preservational styles were defined to recognize plant taphofacies in the studied sequence. Eleven taphofacies were identified and plant sources within a volcanic and geothermal system are proposed. Plant remains are of autochthonous to para-autochthonous origin and best preservation was found in distal facies of siliceous hot spring (sinter) systems. Lateral and vertical taphonomic differences were found in the studied sequence. These are due to changes in the sedimentary input and distance to the geothermal fluids. Results enable the reconstruction of the depositional history of this region of the Deseado Massif geological Province. We infer formation of a hot-spring (sinter) system that was subsequently destroyed by a phreatic eruption process at the margin of an andesitic effusive dome in partially reworked fall pyroclastic subfacies. After the destruction of the geothermal system, a fluvial and lacustrine epiclastic subfacies developed preserving a plant community typical of the Middle-Late Jurassic of Gondwana. Later, volcanic activity produced pyroclastic subfacies, with thick ash-fall and flow deposits from different sources and separated by a time gap that promoted fossilization of an in situ forest. Taphonomic studies of these plant communities allowed reconstruction of a chain of geological events and how these processes have influenced the preservation of a Jurassic flora from Patagonia, thus contributing to an understanding of the paleoecology of the Deseado Massif geological province.
摘要在阿根廷圣克鲁斯省的Laguna Flecha Negra地区（Bahía Laura Complex，侏罗纪中晚期）进行了地质研究。定义了沉积相和保存样式，以识别所研究序列中的植物分支相。确定了11个分支相，并提出了火山和地热系统内的植物来源。植物遗骸具有本地-准本地起源，保存最好的是硅质温泉（烧结）系统的远端相。在所研究的序列中发现了横向和垂直的taphonomic差异。这是由于沉积输入和与地热流体的距离发生了变化。这些结果使人们能够重建德塞多地块地质省这一地区的沉积历史。我们推断出温泉（烧结矿）系统的形成，该系统随后被部分改造的秋季火山碎屑亚相中安山岩溢流圆顶边缘的潜水喷发过程破坏。地热系统破坏后，河流和湖泊表碎屑亚相发育，保留了冈瓦纳大陆中晚侏罗世的典型植物群落。后来，火山活动产生了火山碎屑亚相，有来自不同来源的厚厚的火山灰降落和流动沉积物，并被时间间隔分隔开，这促进了原位森林的石化。对这些植物群落的人类学研究使我们能够重建一系列地质事件，以及这些过程如何影响巴塔哥尼亚侏罗纪植物群的保存，从而有助于了解Deseado Massif地质省的古生态。
{"title":"Plant Taphonomy and Paleoenvironment of the Bahía Laura Complex, Middle–Late Jurassic, at the Laguna Flecha Negra Locality (Santa Cruz Province, Argentina)","authors":"A. J. Sagasti, D. Guido, J. G. García Massini, K. Campbell","doi":"10.5710/AMGH.11.11.2020.3395","DOIUrl":"https://doi.org/10.5710/AMGH.11.11.2020.3395","url":null,"abstract":"Abstract. Taphonomic studies were carried out at Laguna Flecha Negra locality (Bahía Laura Complex, Middle–Late Jurassic), Santa Cruz Province, Argentina. Sedimentary facies and preservational styles were defined to recognize plant taphofacies in the studied sequence. Eleven taphofacies were identified and plant sources within a volcanic and geothermal system are proposed. Plant remains are of autochthonous to para-autochthonous origin and best preservation was found in distal facies of siliceous hot spring (sinter) systems. Lateral and vertical taphonomic differences were found in the studied sequence. These are due to changes in the sedimentary input and distance to the geothermal fluids. Results enable the reconstruction of the depositional history of this region of the Deseado Massif geological Province. We infer formation of a hot-spring (sinter) system that was subsequently destroyed by a phreatic eruption process at the margin of an andesitic effusive dome in partially reworked fall pyroclastic subfacies. After the destruction of the geothermal system, a fluvial and lacustrine epiclastic subfacies developed preserving a plant community typical of the Middle-Late Jurassic of Gondwana. Later, volcanic activity produced pyroclastic subfacies, with thick ash-fall and flow deposits from different sources and separated by a time gap that promoted fossilization of an in situ forest. Taphonomic studies of these plant communities allowed reconstruction of a chain of geological events and how these processes have influenced the preservation of a Jurassic flora from Patagonia, thus contributing to an understanding of the paleoecology of the Deseado Massif geological province.","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":"58 1","pages":"207 - 222"},"PeriodicalIF":1.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45112218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-30DOI: 10.5710/AMGH.04.01.2021.3377
M. Alvarez, Claudia J. del Río
Abstract. The endemic Patagonian genus Titomaya gen. nov. is erected to include the Danian Meretrix chalcedonica (Lefipan and Salamanca formations) and Titomaya longobucca sp. nov. (Salamanca Formation) from the Chubut Province (Argentina). Although Meretrix and Titomaya share the same characteristic sculpture of their nymphs, Titomaya is differentiated by having medium to small, subtriangular, higher than long shells, a narrower and shorter hinge plate, smaller cardinal and anterior teeth, and by the development of a deeper pallial sinus. This new genus rules out the presence of Meretrix in Patagonia, as was long believed, and increases the list of endemic taxa that characterize the Danian assemblages of Patagonia.
{"title":"A New Veneroid Genus (Mollusca: Bivalvia) of the Danian of Patagonia (Chubut Province, Argentina)","authors":"M. Alvarez, Claudia J. del Río","doi":"10.5710/AMGH.04.01.2021.3377","DOIUrl":"https://doi.org/10.5710/AMGH.04.01.2021.3377","url":null,"abstract":"Abstract. The endemic Patagonian genus Titomaya gen. nov. is erected to include the Danian Meretrix chalcedonica (Lefipan and Salamanca formations) and Titomaya longobucca sp. nov. (Salamanca Formation) from the Chubut Province (Argentina). Although Meretrix and Titomaya share the same characteristic sculpture of their nymphs, Titomaya is differentiated by having medium to small, subtriangular, higher than long shells, a narrower and shorter hinge plate, smaller cardinal and anterior teeth, and by the development of a deeper pallial sinus. This new genus rules out the presence of Meretrix in Patagonia, as was long believed, and increases the list of endemic taxa that characterize the Danian assemblages of Patagonia.","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":"58 1","pages":"112 - 121"},"PeriodicalIF":1.0,"publicationDate":"2021-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48060997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-30DOI: 10.5710/AMGH.01.03.2021.3389
Maurice Guicharrousse-Vargas, Jaime A. Villafaña, J. Carrillo-Briceño, Pablo Oyanadel-Urbina, Romina Figueroa, J. Pérez-Marín, M. Rivadeneira, J. Kriwet
Abstract. We present the first fossil record of the sawshark genus Pliotrema from the south-eastern Pacific Ocean. The examined material was obtained from a little-known fossil locality named “Arenas de Caldera” in the Atacama Region of Chile. The fossiliferous deposits belong to the Bahía Inglesa Formation, which is most likely middle Miocene–early Pliocene in age. There are no extant species of this sawfish in the eastern Pacific, probably due to the onset of cooling conditions during the Neogene. The type of environment for the elasmobranchs reported in this study is interpreted as demersal, based on the bathymetric affinities of extant species. Our results show that future studies are needed to better understand the evolutionary history and past distributions of this sawshark genus and their implications on current biogeographic patterns.
{"title":"The First Fossil Record of the Sawshark Pliotrema (Pristiophoridae) from the Neogene of the Southeastern Pacific (Chile)","authors":"Maurice Guicharrousse-Vargas, Jaime A. Villafaña, J. Carrillo-Briceño, Pablo Oyanadel-Urbina, Romina Figueroa, J. Pérez-Marín, M. Rivadeneira, J. Kriwet","doi":"10.5710/AMGH.01.03.2021.3389","DOIUrl":"https://doi.org/10.5710/AMGH.01.03.2021.3389","url":null,"abstract":"Abstract. We present the first fossil record of the sawshark genus Pliotrema from the south-eastern Pacific Ocean. The examined material was obtained from a little-known fossil locality named “Arenas de Caldera” in the Atacama Region of Chile. The fossiliferous deposits belong to the Bahía Inglesa Formation, which is most likely middle Miocene–early Pliocene in age. There are no extant species of this sawfish in the eastern Pacific, probably due to the onset of cooling conditions during the Neogene. The type of environment for the elasmobranchs reported in this study is interpreted as demersal, based on the bathymetric affinities of extant species. Our results show that future studies are needed to better understand the evolutionary history and past distributions of this sawshark genus and their implications on current biogeographic patterns.","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":"58 1","pages":"122 - 131"},"PeriodicalIF":1.0,"publicationDate":"2021-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45971378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-30DOI: 10.5710/AMGH.30.12.2020.3379
S. Brizuela, Daniel Tassara
Only two giant vampire fossils are so far recognize at mid latitude in the late Pleistocene of South America. Both considered with reasonable doubt (cf., aff.) to Desmodus draculae. Here, a recently recovered dentary form the late Pleistocene of southeastern Buenos Aires, is confidently assigned to D. draculae. During the late Pleistocene D. draculae had a large distribution from Mexico to central Argentina, larger than that of extant D. rotundus.
{"title":"New Record of the Vampire Desmodus draculae (Chiroptera) from the Late Pleistocene of Argentina","authors":"S. Brizuela, Daniel Tassara","doi":"10.5710/AMGH.30.12.2020.3379","DOIUrl":"https://doi.org/10.5710/AMGH.30.12.2020.3379","url":null,"abstract":"Only two giant vampire fossils are so far recognize at mid latitude in the late Pleistocene of South America. Both considered with reasonable doubt (cf., aff.) to Desmodus draculae. Here, a recently recovered dentary form the late Pleistocene of southeastern Buenos Aires, is confidently assigned to D. draculae. During the late Pleistocene D. draculae had a large distribution from Mexico to central Argentina, larger than that of extant D. rotundus.","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":"58 1","pages":"169 - 176"},"PeriodicalIF":1.0,"publicationDate":"2021-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44311009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-30DOI: 10.5710/AMGH.17.02.2021.3390
L. A. Giraldo, C. Labandeira, Fabiany Herrera, M. Carvalho
Abstract. Plant predation by insects is a major driver of high plant diversity in modern tropical forests. Previous reports of leaf damage in middle–late Paleocene Neotropical rainforests of Cerrejón, Colombia, show that leaf herbivory was abundant but of low diversity, mainly inflicted by generalized feeders. Here, we present and describe plant-insect associations in leaf fossils from the middle–late Paleocene Bogotá Formation, central Colombia, to test whether the high abundance and low richness of insect damage typified early evolving Neotropical rainforests. The Bogotá flora records the highest richness and frequency of insect-damage associations among comparable Paleocene floras in North America, Patagonia, and Europe, as well as the highest number of leaf mines and galling associations. These results indicate that by the middle–late Paleocene, plant-insect herbivore interactions were much more intense and host-specialized in Neotropical rainforests of the Bogotá region than elsewhere. The rich and frequent galling associations, a distinctive feature of the Bogotá flora, are consistent with the preferential use of canopy leaves by galling insects seen in modern Neotropical rainforests. Our results also indicate differences in plant-insect associations among Paleocene Neotropical rainforests, perhaps reflecting a geographically heterogeneous ecological recovery from the end-Cretaceous ecological crisis. Plant insect-associations in the Bogotá flora also suggest a deep historical context for negative density-dependence as a potential driver (and maintainer) of the high plant diversity observed in modern Neotropical rainforests.
{"title":"Rich and Specialized Plant-Insect Associations in a Middle–Late Paleocene (58–60 Ma) Neotropical Rainforest (Bogotá Formation, Colombia)","authors":"L. A. Giraldo, C. Labandeira, Fabiany Herrera, M. Carvalho","doi":"10.5710/AMGH.17.02.2021.3390","DOIUrl":"https://doi.org/10.5710/AMGH.17.02.2021.3390","url":null,"abstract":"Abstract. Plant predation by insects is a major driver of high plant diversity in modern tropical forests. Previous reports of leaf damage in middle–late Paleocene Neotropical rainforests of Cerrejón, Colombia, show that leaf herbivory was abundant but of low diversity, mainly inflicted by generalized feeders. Here, we present and describe plant-insect associations in leaf fossils from the middle–late Paleocene Bogotá Formation, central Colombia, to test whether the high abundance and low richness of insect damage typified early evolving Neotropical rainforests. The Bogotá flora records the highest richness and frequency of insect-damage associations among comparable Paleocene floras in North America, Patagonia, and Europe, as well as the highest number of leaf mines and galling associations. These results indicate that by the middle–late Paleocene, plant-insect herbivore interactions were much more intense and host-specialized in Neotropical rainforests of the Bogotá region than elsewhere. The rich and frequent galling associations, a distinctive feature of the Bogotá flora, are consistent with the preferential use of canopy leaves by galling insects seen in modern Neotropical rainforests. Our results also indicate differences in plant-insect associations among Paleocene Neotropical rainforests, perhaps reflecting a geographically heterogeneous ecological recovery from the end-Cretaceous ecological crisis. Plant insect-associations in the Bogotá flora also suggest a deep historical context for negative density-dependence as a potential driver (and maintainer) of the high plant diversity observed in modern Neotropical rainforests.","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":"58 1","pages":"75 - 99"},"PeriodicalIF":1.0,"publicationDate":"2021-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42674263","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-30DOI: 10.5710/AMGH.18.01.2021.3416
M. Ezcurra, S. Bandyopadhyay, D. Gower
Abstract. Erythrosuchid archosauriforms are quadrupedal carnivorous reptiles with a proportionally huge skull. They represent one of the first evolutionary radiations of medium to large predatory diapsids after the Permo–Triassic mass extinction. Erythrosuchids are known from Lower–Middle Triassic rocks of South Africa, Russia, and China, and there have been preliminary reports from the Middle Triassic Yerrapalli Formation of south-central India. Here we describe, compare and figure for the first time these Indian erythrosuchid remains. We erect the new genus and species Bharitalasuchus tapani based on a holotype and paratype that preserve tooth-bearing cranial fragments, at least 17 presacral vertebrae, some ribs and probable intercentra, and partial shoulder and pelvic girdles and hindlimb and allow recognizing a series of autapomorphies and unique combination of character states among erythrosuchids. Our phylogenetic analysis recovered Bharitalasuchus tapani most closely related to Shansisuchus shansisuchus and Chalishevia cothurnata from the late Anisian of China and Ladinian of Russia, respectively. The phylogenetic affinities of this new taxon and a revision of the tetrapod assemblage of the Yerrapalli Formation shed light on the age of this unit. The presence of the Wadiasaurus-Rechnisaurus-Bharitalasuchus association in the Yerrapalli Formation closely resembles the Sinokannemeyeria-Shansisuchus dicynodont-erythrosuchid association of late Anisian to early Ladinian Chinese units. This evidence supports a post-early–middle Anisian age, even possibly early Ladinian, for the Yerrapalli Formation. The presence of possibly one of the last erythrosuchids in India would indicate that the clade still retained both a northern and southern Pangean distribution before its extinction.
{"title":"A New Erythrosuchid Archosauriform from the Middle Triassic Yerrapalli Formation of South-Central India","authors":"M. Ezcurra, S. Bandyopadhyay, D. Gower","doi":"10.5710/AMGH.18.01.2021.3416","DOIUrl":"https://doi.org/10.5710/AMGH.18.01.2021.3416","url":null,"abstract":"Abstract. Erythrosuchid archosauriforms are quadrupedal carnivorous reptiles with a proportionally huge skull. They represent one of the first evolutionary radiations of medium to large predatory diapsids after the Permo–Triassic mass extinction. Erythrosuchids are known from Lower–Middle Triassic rocks of South Africa, Russia, and China, and there have been preliminary reports from the Middle Triassic Yerrapalli Formation of south-central India. Here we describe, compare and figure for the first time these Indian erythrosuchid remains. We erect the new genus and species Bharitalasuchus tapani based on a holotype and paratype that preserve tooth-bearing cranial fragments, at least 17 presacral vertebrae, some ribs and probable intercentra, and partial shoulder and pelvic girdles and hindlimb and allow recognizing a series of autapomorphies and unique combination of character states among erythrosuchids. Our phylogenetic analysis recovered Bharitalasuchus tapani most closely related to Shansisuchus shansisuchus and Chalishevia cothurnata from the late Anisian of China and Ladinian of Russia, respectively. The phylogenetic affinities of this new taxon and a revision of the tetrapod assemblage of the Yerrapalli Formation shed light on the age of this unit. The presence of the Wadiasaurus-Rechnisaurus-Bharitalasuchus association in the Yerrapalli Formation closely resembles the Sinokannemeyeria-Shansisuchus dicynodont-erythrosuchid association of late Anisian to early Ladinian Chinese units. This evidence supports a post-early–middle Anisian age, even possibly early Ladinian, for the Yerrapalli Formation. The presence of possibly one of the last erythrosuchids in India would indicate that the clade still retained both a northern and southern Pangean distribution before its extinction.","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":"58 1","pages":"132 - 168"},"PeriodicalIF":1.0,"publicationDate":"2021-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43207297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-30DOI: 10.5710/AMGH.11.12.2020.3391
Hugo I. Martínez-Cabrera, Emilio Estrada-Ruiz
Abstract. Community assembly processes (environmental filtering and limiting similarity) determine the values of quantitative functional traits within communities. The environment influences the number of viable functional strategies species might take. A strong effect of environmental filtering often results in communities having species with similar trait values and narrow functional niches. On the other hand, resource competition (i.e., limiting similarity) leads to communities with broader functional spaces and smaller niche overlap among competing species. The degree to which community assembly processes influence wood trait variation has important implications for paleoclimate estimation using fossil woods since the central tenet of the approach is environmental-driven trait convergence, which assumes a central role of environmental filtering. To infer the strength of these two community assembly forces, we used a functional diversity approach to determine how three wood anatomical traits vary in 14 extant communities (272 species) growing under different climates. We found smaller functional spaces in communities growing in dry/cool places, suggesting that trait convergence could be the result of more robust habitat filtering in these communities. A weaker environmental filtering in warm/wet environments, likely results in an amplification of other drivers that promote a higher number of hydraulic strategies through niche partition in highly structured communities. More complex ecological structures in mild, tropical places likely lead to a higher spread of wood trait values. This asymmetry in the strength of environmental filtering along climate gradients suggests that this differential strength of the trait-climate convergence should be incorporated in paleoclimate prediction models.
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