Pub Date : 2022-01-06DOI: 10.5710/AMGH.16.09.2021.3441
Luciano A. Pradelli, J. Leardi, M. Ezcurra
Abstract. An important parameter in studying the macroevolutionary history of a clade is the variation of its body size. However, the analysis of this parameter in archosauromorphs has been restricted to Archosauria, and the disparity in body size has not been exhaustively explored. In the present work, we study the variation in body size of more than 400 known Permian–Early Jurassic archosauromorph species in the context of their early evolutionary radiation. We analysed the disparity of body size over time and the relationship between this parameter and the palaeolatitudinal distribution of species. From these analyses, it was found that the disparity of body size of archosauromorphs increased after the Permian/Triassic boundary. In the case of Pseudosuchia and Pan-Aves (=Avemetatarsalia), the Triassic/Jurassic extinction shows a pattern of selective extinction of medium to large-sized forms, and their body size disparity decreased significantly. In contrast, dinosaurs increased their body size and their disparity did not change significantly after the Triassic/Jurassic extinction event. Regarding the relationship between body size and geographic distribution, pseudosuchians show a pattern of body size decrease towards higher palaeolatitudes, i.e., a converse Bergmann's rule. These results could be linked to physiological factors since many groups of extant ectothermic animals show a similar pattern. These analyses help to elucidate the complex body size evolutionary dynamics in the early radiation of Archosauromorpha, as indicated by the different patterns observed across its subclades.
{"title":"Body Size Disparity of the Archosauromorph Reptiles during the First 90 Million Years of Their Evolution","authors":"Luciano A. Pradelli, J. Leardi, M. Ezcurra","doi":"10.5710/AMGH.16.09.2021.3441","DOIUrl":"https://doi.org/10.5710/AMGH.16.09.2021.3441","url":null,"abstract":"Abstract. An important parameter in studying the macroevolutionary history of a clade is the variation of its body size. However, the analysis of this parameter in archosauromorphs has been restricted to Archosauria, and the disparity in body size has not been exhaustively explored. In the present work, we study the variation in body size of more than 400 known Permian–Early Jurassic archosauromorph species in the context of their early evolutionary radiation. We analysed the disparity of body size over time and the relationship between this parameter and the palaeolatitudinal distribution of species. From these analyses, it was found that the disparity of body size of archosauromorphs increased after the Permian/Triassic boundary. In the case of Pseudosuchia and Pan-Aves (=Avemetatarsalia), the Triassic/Jurassic extinction shows a pattern of selective extinction of medium to large-sized forms, and their body size disparity decreased significantly. In contrast, dinosaurs increased their body size and their disparity did not change significantly after the Triassic/Jurassic extinction event. Regarding the relationship between body size and geographic distribution, pseudosuchians show a pattern of body size decrease towards higher palaeolatitudes, i.e., a converse Bergmann's rule. These results could be linked to physiological factors since many groups of extant ectothermic animals show a similar pattern. These analyses help to elucidate the complex body size evolutionary dynamics in the early radiation of Archosauromorpha, as indicated by the different patterns observed across its subclades.","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":"59 1","pages":"47 - 77"},"PeriodicalIF":1.0,"publicationDate":"2022-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46227779","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 : 2022-01-06DOI: 10.5710/AMGH.16.09.2021.3448
Damián Ruiz-Ramoni, Xiaomin Wang, A. Rincón
Abstract. There are three extant species of wild canids in Venezuela: Urocyon cinereoargenteus, Cerdocyon thous, and Speothos venaticus, excluding the feral domestic dog (Canis familiaris). However, a review of paleontological material that was published previously, along with newly reported ancient specimens, reveals a distinct historical diversity for the same region. The gray fox, U. cinereoargenteus, is the only small-sized taxon and the only Vulpini (true fox) identified to date in the fossil record of Venezuela; its presence is limited to the late Pleistocene of the Mene de Inciarte site, Zulia State. In contrast, large canids are more abundant. Aenocyon dirus (subtribe Canina), the dire wolf from the late Pleistocene, was reported from the sites El Mene de Inciarte, Muaco in Falcón State, and for the first time in El Breal de Orocual (ORS20) in Monagas State. The genus Protocyon, a native South American canid (subtribe Cerdocyonina), is recognized in the country from late Pleistocene Inciarte (Protocyon troglodytes sensu lato), and late Pliocene–early Pleistocene Orocual (ORS16) (Protocyon orocualensis sp. nov.). Finally, we report a possible genus Theriodictis from the late Pleistocene Orocual; this is a Cerdocyonina not previously mentioned for the northern region of South America. These records present broader diversity and suggest a more complex evolutionary history than previously thought for South American canids.
摘要委内瑞拉现存的野生犬科动物有三种:Urocyon cinereogenteus、Cerdocyon thous和Speothos venaticus，不包括野狗(Canis familiaris)。然而，对先前发表的古生物材料的回顾，以及新报道的古代标本，揭示了同一地区独特的历史多样性。灰狐，美国灰狐，是迄今为止在委内瑞拉化石记录中发现的唯一的小型分类群和唯一的狐属(真正的狐狸);它的存在仅限于晚更新世的Mene de incarte遗址，苏利亚州。相比之下，大型犬科动物数量更多。在Falcón州的El Mene de Inciarte、Muaco遗址和Monagas州的El Breal de Orocual (ORS20)遗址首次报道了晚更新世的恐狼Aenocyon dius (Canina亚部落)。Protocyon属是一种土生土长的南美犬科动物(Cerdocyonina亚部落)，在国内从晚更新世的incarte (Protocyon troglodytes sensu lato)和晚更新世-早更新世的orococual (ORS16) (Protocyon orocualensis sp. 11 .)中被发现。最后，我们报道了一个可能来自晚更新世Orocual的Theriodictis属;这是一种以前没有提到的南美洲北部地区的Cerdocyonina。这些记录显示了更广泛的多样性，并表明南美洲犬科动物的进化史比以前认为的要复杂得多。
{"title":"Canids (Caninae) from the Past of Venezuela","authors":"Damián Ruiz-Ramoni, Xiaomin Wang, A. Rincón","doi":"10.5710/AMGH.16.09.2021.3448","DOIUrl":"https://doi.org/10.5710/AMGH.16.09.2021.3448","url":null,"abstract":"Abstract. There are three extant species of wild canids in Venezuela: Urocyon cinereoargenteus, Cerdocyon thous, and Speothos venaticus, excluding the feral domestic dog (Canis familiaris). However, a review of paleontological material that was published previously, along with newly reported ancient specimens, reveals a distinct historical diversity for the same region. The gray fox, U. cinereoargenteus, is the only small-sized taxon and the only Vulpini (true fox) identified to date in the fossil record of Venezuela; its presence is limited to the late Pleistocene of the Mene de Inciarte site, Zulia State. In contrast, large canids are more abundant. Aenocyon dirus (subtribe Canina), the dire wolf from the late Pleistocene, was reported from the sites El Mene de Inciarte, Muaco in Falcón State, and for the first time in El Breal de Orocual (ORS20) in Monagas State. The genus Protocyon, a native South American canid (subtribe Cerdocyonina), is recognized in the country from late Pleistocene Inciarte (Protocyon troglodytes sensu lato), and late Pliocene–early Pleistocene Orocual (ORS16) (Protocyon orocualensis sp. nov.). Finally, we report a possible genus Theriodictis from the late Pleistocene Orocual; this is a Cerdocyonina not previously mentioned for the northern region of South America. These records present broader diversity and suggest a more complex evolutionary history than previously thought for South American canids.","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":"59 1","pages":"97 - 116"},"PeriodicalIF":1.0,"publicationDate":"2022-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44569589","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 : 2022-01-06DOI: 10.5710/AMGH.29.09.2021.3447
J. Fleagle, Justin T. Gladman, R. F. Kay
Abstract. We describe a well-preserved humerus of Homunculus patagonicus, a stem platyrrhine from the late early Miocene of the Santa Cruz Formation, Santa Cruz Province, Argentina. The distal part of a humerus was collected by Carlos Ameghino and figured in the 19th Century, but is now lost. Other described postcranial elements, also collected by him include a femur and a partial radius. Comparative observations are made with living and extinct platyrrhines, Oligocene African anthropoids, and extant strepsirrhines. Homunculus patagonicus was a robustly built arboreal quadruped that weighed between 2.2 and 2.6 kg. There is no evidence that the elbow could be fully extended as in living suspensory platyrrhines like Ateles. The medial orientation of the epicondyle suggests that the finger and wrist flexors were not aligned with the long axis of the limb, a distinction from more cursorial monkeys (extant cercopithecoids and the Cuban Pleistocene fossil platyrrhine Paralouatta have retroflexed medial epicondyles). Overall, the morphology is typically platyrrhine although the bone is quite robust. The robustness of the humerus is most comparable to that of early anthropoids from Africa rather than any extant platyrrhine.
{"title":"A New Humerus of Homunculus patagonicus, a Stem Platyrrhine from the Santa Cruz Formation (Late Early Miocene), Santa Cruz Province, Argentina","authors":"J. Fleagle, Justin T. Gladman, R. F. Kay","doi":"10.5710/AMGH.29.09.2021.3447","DOIUrl":"https://doi.org/10.5710/AMGH.29.09.2021.3447","url":null,"abstract":"Abstract. We describe a well-preserved humerus of Homunculus patagonicus, a stem platyrrhine from the late early Miocene of the Santa Cruz Formation, Santa Cruz Province, Argentina. The distal part of a humerus was collected by Carlos Ameghino and figured in the 19th Century, but is now lost. Other described postcranial elements, also collected by him include a femur and a partial radius. Comparative observations are made with living and extinct platyrrhines, Oligocene African anthropoids, and extant strepsirrhines. Homunculus patagonicus was a robustly built arboreal quadruped that weighed between 2.2 and 2.6 kg. There is no evidence that the elbow could be fully extended as in living suspensory platyrrhines like Ateles. The medial orientation of the epicondyle suggests that the finger and wrist flexors were not aligned with the long axis of the limb, a distinction from more cursorial monkeys (extant cercopithecoids and the Cuban Pleistocene fossil platyrrhine Paralouatta have retroflexed medial epicondyles). Overall, the morphology is typically platyrrhine although the bone is quite robust. The robustness of the humerus is most comparable to that of early anthropoids from Africa rather than any extant platyrrhine.","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":"59 1","pages":"78 - 96"},"PeriodicalIF":1.0,"publicationDate":"2022-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45593337","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 : 2021-10-31DOI: 10.5710/AMGH.06.08.2021.3439
Sebastián Echarri, Karen Ulloa-Guaiquin, Guillermo Aguirrezabala, A. Forasiepi
1Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"-CONICET. Av. Ángel Gallardo 470, C1405DJR Ciudad Autónoma de Buenos Aires, Argentina. 2Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA), CONICET-Universidad Nacional del Comahue. Quintral 1250, R8400FRF San Carlos de Bariloche, Argentina. 3Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA), CCT-CONICET, Mendoza. Av. Ruiz Leal s/no, 5500 Mendoza, Argentina. SEBASTIAN ECHARRI1 KAREN S. ULLOA-GUAIQUIN2 GUILLERMO AGUIRREZABALA2 ANALIA M. FORASIEPI3
阿根廷自然科学博物馆“Bernardino Rivadavia”-Conicet。AV公司。Angel Gallardo 470，C1405DJR阿根廷布宜诺斯艾利斯自治市。Comahue国立大学生物多样性与环境研究所。Quintral 1250，R8400FRF San Carlos de Bariloche，阿根廷。3阿根廷尼沃洛吉亚、冰川和环境科学研究所，CCT-Conicet，门多萨。AV公司。Ruiz Leal S/No，5500 Mendoza，阿根廷。塞巴斯蒂安·埃查里1凯伦S。乌洛亚-瓜伊金2吉列尔莫·阿吉雷扎巴拉2 Analia M。福萨耶皮3
{"title":"Cladosictis patagonica (Metatheria, Sparassodonta) from the Collón Cura Formation (Middle Miocene), Río Negro, Argentina","authors":"Sebastián Echarri, Karen Ulloa-Guaiquin, Guillermo Aguirrezabala, A. Forasiepi","doi":"10.5710/AMGH.06.08.2021.3439","DOIUrl":"https://doi.org/10.5710/AMGH.06.08.2021.3439","url":null,"abstract":"1Museo Argentino de Ciencias Naturales \"Bernardino Rivadavia\"-CONICET. Av. Ángel Gallardo 470, C1405DJR Ciudad Autónoma de Buenos Aires, Argentina. 2Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA), CONICET-Universidad Nacional del Comahue. Quintral 1250, R8400FRF San Carlos de Bariloche, Argentina. 3Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA), CCT-CONICET, Mendoza. Av. Ruiz Leal s/no, 5500 Mendoza, Argentina. SEBASTIAN ECHARRI1 KAREN S. ULLOA-GUAIQUIN2 GUILLERMO AGUIRREZABALA2 ANALIA M. FORASIEPI3","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":"58 1","pages":"485 - 491"},"PeriodicalIF":1.0,"publicationDate":"2021-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49059852","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 : 2021-10-31DOI: 10.5710/AMGH.05.09.2021.3426
A. Heckert, R. Martínez, Matthew D. Celeskey
Abstract. Aetosaurs are an early-diverging clade of “crocodile-line” archosaurs whose oldest records come from Argentina and Brazil. Articulated skeletons of aetosaurs are rare, but offer insight into their paleobiology. We describe here an incomplete, articulated posterior skeleton of an aetosaur from the Upper Triassic Ischigualasto Formation of San Juan Province, Argentina. It resembles Aetosauroides, the only aetosaur genus currently recognized from the Ischigualasto Formation, but lacks apomorphies that would allow us to assign it to that taxon, appears to be more robust than the holotype of A. scagliai, and preserves a different tail morphology. We identify the specimen as a basal aetosaur in part because the few exposed dorsal and lateral osteoderms have a typical ornamentation of radially distributed pits, grooves, and ridges emanating from a “center of ossification”. Although the specimen is incomplete and exposed primarily in ventral view from the sacrum posteriorly, it preserves many anatomical features not often preserved in aetosaurs, including extensive appendicular armor and a well-preserved caudal ventral carapace. The latter apparently consists of only two columns of ventral osteoderms, and preserves a large cloacal vent proximally. Posteriorly, the ventral paramedian osteoderms fuse to form a single element, something that has not previously been demonstrated in aetosaurs. The arrangement of osteoderms around the vent is distinct from that seen in A. scagliai. The ventral caudal osteoderms differ from many other aetosaurs in that they do not transition from wider than long to longer than wide, indicating that the specimen had a relatively abbreviated tail.
{"title":"Anatomical Details of Aetosauria (Archosauria: Pseudosuchia) as Revealed by an Articulated Posterior Skeleton from the Upper Triassic Ischigualasto Formation, San Juan Province, Argentina","authors":"A. Heckert, R. Martínez, Matthew D. Celeskey","doi":"10.5710/AMGH.05.09.2021.3426","DOIUrl":"https://doi.org/10.5710/AMGH.05.09.2021.3426","url":null,"abstract":"Abstract. Aetosaurs are an early-diverging clade of “crocodile-line” archosaurs whose oldest records come from Argentina and Brazil. Articulated skeletons of aetosaurs are rare, but offer insight into their paleobiology. We describe here an incomplete, articulated posterior skeleton of an aetosaur from the Upper Triassic Ischigualasto Formation of San Juan Province, Argentina. It resembles Aetosauroides, the only aetosaur genus currently recognized from the Ischigualasto Formation, but lacks apomorphies that would allow us to assign it to that taxon, appears to be more robust than the holotype of A. scagliai, and preserves a different tail morphology. We identify the specimen as a basal aetosaur in part because the few exposed dorsal and lateral osteoderms have a typical ornamentation of radially distributed pits, grooves, and ridges emanating from a “center of ossification”. Although the specimen is incomplete and exposed primarily in ventral view from the sacrum posteriorly, it preserves many anatomical features not often preserved in aetosaurs, including extensive appendicular armor and a well-preserved caudal ventral carapace. The latter apparently consists of only two columns of ventral osteoderms, and preserves a large cloacal vent proximally. Posteriorly, the ventral paramedian osteoderms fuse to form a single element, something that has not previously been demonstrated in aetosaurs. The arrangement of osteoderms around the vent is distinct from that seen in A. scagliai. The ventral caudal osteoderms differ from many other aetosaurs in that they do not transition from wider than long to longer than wide, indicating that the specimen had a relatively abbreviated tail.","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":"58 1","pages":"464 - 484"},"PeriodicalIF":1.0,"publicationDate":"2021-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49183919","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 : 2021-10-21DOI: 10.5710/1851-8044-58.5.442
Brian M Davis
{"title":"Amassing the Marvels of Our Southern Past: A Complete (But Far from Final) Collection of Mesozoic South American Paleomammalogy","authors":"Brian M Davis","doi":"10.5710/1851-8044-58.5.442","DOIUrl":"https://doi.org/10.5710/1851-8044-58.5.442","url":null,"abstract":"","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":"58 1","pages":"442 - 444"},"PeriodicalIF":1.0,"publicationDate":"2021-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48414891","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 : 2021-09-30DOI: 10.5710/AMGH.13.08.2021.3446
A. D. Farjat, Mario Suárez Riglos, J. Ortiz
Abstract. Heteroconchia Cardiomorphi bivalves from 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 three Heteroconchia Cardiomorphi genera, but it also includes the description of new findings and first reports of some taxa in the basin. They were collected in nine scattered outcrops in the Interandean and Subandean regions of Bolivia. A total of 22 specimens, well- to regularly-preserved was studied. The genus Pleurodapis, is reported for the first time from Ludlow–Pridoli successions of Alarache, southern Subandean as Pleurodapis sp. A. The cosmopolitan genus Paracyclas is reported in the Central Andean Basin for the first time, from the Middle Devonian of Subandean as Paracyclas? sp. The species Pleurodapis multicincta and Cardiomorpha oblonga, are described from the central Subandean and the Interandean regions for the first time in the basin. This research is also a contribution to understand the distribution and the richness of Silurian and Devonian bivalves in Central Andean Basin and their relations with the surrounding basins of Gondwana.
{"title":"Silurian and Devonian Heteroconchia Cardiomorphi Bivalves from Bolivia","authors":"A. D. Farjat, Mario Suárez Riglos, J. Ortiz","doi":"10.5710/AMGH.13.08.2021.3446","DOIUrl":"https://doi.org/10.5710/AMGH.13.08.2021.3446","url":null,"abstract":"Abstract. Heteroconchia Cardiomorphi bivalves from 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 three Heteroconchia Cardiomorphi genera, but it also includes the description of new findings and first reports of some taxa in the basin. They were collected in nine scattered outcrops in the Interandean and Subandean regions of Bolivia. A total of 22 specimens, well- to regularly-preserved was studied. The genus Pleurodapis, is reported for the first time from Ludlow–Pridoli successions of Alarache, southern Subandean as Pleurodapis sp. A. The cosmopolitan genus Paracyclas is reported in the Central Andean Basin for the first time, from the Middle Devonian of Subandean as Paracyclas? sp. The species Pleurodapis multicincta and Cardiomorpha oblonga, are described from the central Subandean and the Interandean regions for the first time in the basin. This research is also a contribution to understand the distribution and the richness of Silurian and Devonian bivalves in Central Andean Basin and their relations with the surrounding basins of Gondwana.","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":"58 1","pages":"385 - 400"},"PeriodicalIF":1.0,"publicationDate":"2021-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49532801","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 : 2021-09-30DOI: 10.5710/AMGH.13.07.2021.3442
S. Apesteguía, F. Garberoglio, R. O. Gómez
Abstract. The New Zealand tuatara (Sphenodon) is the sole surviving rhynchocephalian of a once thriving group across Pangea during early Mesozoic times. Outside New Zealand, close relatives of the tuatara (sphenodontines) are known from a few Jurassic records in North America and Europe and from end-Cretaceous incomplete remains in Patagonia. Still, the evolutionary relationships of most of them remain elusive. Here we describe a new sphenodontine, Tika giacchinoi gen. et sp. nov., based on well-preserved cranial and postcranial remains from upper levels of the Candeleros Formation (Cenomanian) at the Konservat-Lagerstätte of ‘La Buitrera Paleontological Area’ in northern Patagonia, Argentina. Our phylogenetic analysis recovered Tika as a close relative of the tuatara, together with Laurasian and Patagonian taxa. The new finding represents the oldest certain sphenodontine from the gondwanan continents and reinforces the hypothesis that particular terrestrial ectothermic tetrapods attained a circumantarctic Cretaceous-Tertiary distribution. Tika is inferred to have fed upon a variety of prey items including small vertebrates, similar to the extant tuatara, but ecologically different from the large herbivorous sphenodontians already known from La Buitrera. Therefore the new taxon expands the known diversity of sphenodontians during the Late Cretaceous in Patagonia and indicates that Rhynchocephalia, although declining or extinct in Laurasia, were still taxonomic and ecologically diverse in southwestern Gondwana.
{"title":"Earliest Tuatara Relative (Lepidosauria: Sphenodontinae) from Southern Continents","authors":"S. Apesteguía, F. Garberoglio, R. O. Gómez","doi":"10.5710/AMGH.13.07.2021.3442","DOIUrl":"https://doi.org/10.5710/AMGH.13.07.2021.3442","url":null,"abstract":"Abstract. The New Zealand tuatara (Sphenodon) is the sole surviving rhynchocephalian of a once thriving group across Pangea during early Mesozoic times. Outside New Zealand, close relatives of the tuatara (sphenodontines) are known from a few Jurassic records in North America and Europe and from end-Cretaceous incomplete remains in Patagonia. Still, the evolutionary relationships of most of them remain elusive. Here we describe a new sphenodontine, Tika giacchinoi gen. et sp. nov., based on well-preserved cranial and postcranial remains from upper levels of the Candeleros Formation (Cenomanian) at the Konservat-Lagerstätte of ‘La Buitrera Paleontological Area’ in northern Patagonia, Argentina. Our phylogenetic analysis recovered Tika as a close relative of the tuatara, together with Laurasian and Patagonian taxa. The new finding represents the oldest certain sphenodontine from the gondwanan continents and reinforces the hypothesis that particular terrestrial ectothermic tetrapods attained a circumantarctic Cretaceous-Tertiary distribution. Tika is inferred to have fed upon a variety of prey items including small vertebrates, similar to the extant tuatara, but ecologically different from the large herbivorous sphenodontians already known from La Buitrera. Therefore the new taxon expands the known diversity of sphenodontians during the Late Cretaceous in Patagonia and indicates that Rhynchocephalia, although declining or extinct in Laurasia, were still taxonomic and ecologically diverse in southwestern Gondwana.","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":"58 1","pages":"416 - 441"},"PeriodicalIF":1.0,"publicationDate":"2021-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47761749","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 : 2021-09-30DOI: 10.5710/AMGH.23.07.2021.3412
Jeremías R. A. Taborda, J. Desojo, E. Dvorkin
Abstract. Aetosaurs are quadrupedal archosaurs that had a worldwide distribution during the Late Triassic. They had small heads relative to their body size and a long tail, and they are characterized by a dorsal and ventral carapace formed by ornamented and articulated osteoderms. Although aetosaurs historically have been considered the only herbivorous among the early pseudosuchian archosaurs, few analyses quantitatively assess their feeding habits, and some authors have proposed omnivorous and/or scavenging habits for the group. Neoaetosauroides engaeus is an aetosaur from the Late Triassic of the Los Colorados Formation, La Rioja, Argentina. N. engaeus is known from three relatively well-preserved skulls, making it an excellent taxon to study the feeding ecology. We applied the Finite Element Method to estimate bite force and to evaluate the structural response of the skull at different positions during food processing. Our results show that the skull of N. engaeus generated a bite force of 3.6 kN, a magnitude comparable with the measurement made in Alligator mississippiensis, and could resist lateral and longitudinal forces during feeding. This indicates that N. engaeus was capable of hunting of small living prey (e.g., cynodonts) with its jaws, and/or dragging carcasses of larger sizes (e.g., dicynodonts). These results bring new evidence that supports possible zoophagy or omnivory for N. engaeus, thus expanding the potential ecological roles of aetosaurs.
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