scholarly journals Earliest Palaeocene purgatoriids and the initial radiation of stem primates

2021 ◽  
Vol 8 (2) ◽  
pp. 210050
Author(s):  
Gregory P. Wilson Mantilla ◽  
Stephen G. B. Chester ◽  
William A. Clemens ◽  
Jason R. Moore ◽  
Courtney J. Sprain ◽  
...  

Plesiadapiform mammals, as stem primates, are key to understanding the evolutionary and ecological origins of Pan-Primates and Euarchonta. The Purgatoriidae, as the geologically oldest and most primitive known plesiadapiforms and one of the oldest known placental groups, are also central to the evolutionary radiation of placentals and the Cretaceous-Palaeogene biotic recovery on land. Here, we report new dental fossils of Purgatorius from early Palaeocene (early Puercan) age deposits in northeastern Montana that represent the earliest dated occurrences of plesiadapiforms. We constrain the age of these earliest purgatoriids to magnetochron C29R and most likely to within 105–139 thousand years post-K/Pg boundary. Given the occurrence of at least two species, Purgatorius janisae and a new species, at the locality, we provide the strongest support to date that purgatoriids and, by extension, Pan-Primates, Euarchonta and Placentalia probably originated by the Late Cretaceous. Within 1 million years of their arrival in northeastern Montana, plesiadapiforms outstripped archaic ungulates in numerical abundance and dominated the arboreal omnivore–frugivore niche in mammalian local faunas.

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5594 ◽  
Author(s):  
Agustín G. Martinelli ◽  
Thiago S. Marinho ◽  
Fabiano V. Iori ◽  
Luiz Carlos B. Ribeiro

Field work conducted by the staff of the Centro de Pesquisas Paleontológicas Llewellyn Ivor Price of the Universidade Federal do Triângulo Mineiro since 2009 at Campina Verde municipality (MG) have resulted in the discovery of a diverse vertebrate fauna from the Adamantina Formation (Bauru Basin). The baurusuchidCampinasuchus diniziwas described in 2011 from Fazenda Três Antas site and after that, preliminary descriptions of a partial crocodyliform egg, abelisaurid teeth, and fish remains have been done. Recently, the fossil sample has been considerably increased including the discovery of several, partially articulated fish remains referred to Lepisosteiformes and an almost complete and articulated skeleton referred to a new species ofCaipirasuchus(Notosuchia, Sphagesauridae), which is the main subject of this contribution. At present, this genus was restricted to the Adamantina Formation cropping out in São Paulo state, with the speciesCaipirasuchus montealtensis,Caipirasuchus paulistanus, andCaipirasuchus stenognathus. The new material represents the holotype of a new species,Caipirasuchus mineirusn. sp., diferenciated from the previously ones due to the following traits: last two maxillary teeth located posterior to anterior edge of infraorbital fenestra, elongated lateroventral maxillo-jugal suture—about ½ the anteroposterior maxillar length—and contact between posterior crest of quadrate and posterior end of squamosal forming an almost 90° flaring roof of the squamosal, among others.C. mineiruswas found in the same outcrop thanCampinasuchusbut stratigraphically the former occurs in the lower portion of the section with no unambiguous data supporting the coexistance of both taxa.


Author(s):  
Ren Hirayama

A nearly complete shell of the genus Adocus (Adocidae; Pan-Trionychia; Cryptodira; Testudines) was collected from the late Cretaceous (Turonian) Tamagawa Formation of Kuji Group at Kuji City, Iwate Prefecture, northeast Japan. This turtle shows unique features such as the loss of cervical scute, extreme expansion of marginal scutes overlying costal plates, and exclusion of the humeral- pectoral sulcus from entoplastron. Thus, A. kohaku is erected as a new species. As A. kohaku shows most derived position of A. kohaku within this genus, morphological diversity of the genus Adocus seems to have occurred rather early in its evolution in Eastern Asia.


2020 ◽  
Vol 13 (1) ◽  
pp. 24-33
Author(s):  
Antonio Arnaiz-Villena ◽  
Valentín Ruiz-del-Valle ◽  
Fabio Suarez-Trujillo ◽  
Adrian Lopez-Nares ◽  
Alvaro Callado ◽  
...  

Introduction: South American siskins (Genus Carduelis/Spinus) are the outcome of regional evolutionary radiation from an extant (or other extinct) species: C. notata, a North America siskin, which thrives in Mexico subtropical areas and is parental of one of the three described North American siskin radiations. Methods: Speciation and/or subspeciation of this South American siskin radiation have probably occurred during Pleistocene Epoch. In the present paper, a new species/subspecies akin to C./S. atrata is described by genetic and phenotypic parameters: this new species/subspecies was previously considered a subspecies of C./S. xanthogastra, which thrives further North and is separated about 1,762 km, 1,094 miles, from this described subspecies, Carduelis/ Spinus xanthogastra stejnegeri. Results: Our genetic study using mt cyt b, phenotypic and behavior observations show that this putative C./S. xanthogastra subspecies is either a different species or a C./S. atrata subspecies; we have proposed a provisional name for this finch, C./S. lapazensis, instead of C./S. x. stejnegeri. Conclusion: Species definition is movable and controversial, and it is uncertain in South American siskins, which all show a close genetic and phenotypical relationship, which may be still immersed in speciation processes since Pleistocene Epoch.


2020 ◽  
Vol 191 ◽  
pp. 1
Author(s):  
Danièle Gaspard ◽  
Sylvain Charbonnier

Many Cretaceous asymmetrical rhynchonellid brachiopods (Brachiopoda, Rhynchonellida) have long been considered as Rhynchonella difformis (Valenciennes in Lamarck, 1819). After a revision, Owen (1962) included the Cenomanian specimens from Europe in Cyclothyris M’Coy, 1844. Later, Manceñido et al. (2002) confirmed this decision and critically mentioned the name of another asymmetrical rhynchonellid genus from Spain, Owenirhynchia Calzada in Calzada and Pocovi, 1980. Specimens with an asymmetrical anterior margin (non particularly ecophenotypical), from the Late Coniacian and the Santonian of Les Corbières (Aude, France) and Basse-Provence (SE France) are here compared to specimens of the original Cenomanian species C. difformis. They are also compared to new material from the Northern Castilian Platform (Coniacian-Santonian, N Spain) and to Rhynchonella globata Arnaud, 1877 (Campanian, Les Charentes, Dordogne, SW France) and Rh. vesicularis Coquand, 1860 (Campanian, Charente, SW France). These observations document the great morphological diversity among all these species and lead us to erect a new species: Cyclothyris grimargina nov. sp. from the type material of Arnaud, and two new genera: Contortithyris nov. gen. including Contortithyris thermae nov. sp., Beaussetithyris nov. gen. including Beaussetithyris asymmetrica nov. sp. All of these brachiopods fundamentally present an asymmetrical state which origin is discussed.


Zootaxa ◽  
2018 ◽  
Vol 4527 (4) ◽  
pp. 588
Author(s):  
ALBERTO ARANO-RUIZ ◽  
LAZARO W. VIÑOLA-LÓPEZ ◽  
REINALDO ROJAS-CONSUEGRA ◽  
CARLOS RAFAEL BORGES-SELLEN

A new species of raninid crustacean, Vegaranina rivasi sp. nov, is described based on three specimens collected from a Late Cretaceous deposit in central Cuba. Previous studies assigned one of the specimens to Vegaranina precocia (Feldmann, Vega, Tucker, Garcia-Barrera & Avendano, 1996), a species described from the Late Cretaceous of Mexico. However, after collecting the new specimens and recent major revisions of the group, we identified a unique combination of characters in the Cuban specimens that separate them from the other species in the genus. 


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