Pucatherium
| Pucatherium | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Osteoderms of Pucatherium |
||||||||||||
| Temporal occurrence | ||||||||||||
| Middle to Upper Eocene | ||||||||||||
| 41.3 to 33.3 million years | ||||||||||||
| Locations | ||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Pucatherium | ||||||||||||
| Herrera , Powell & del Papa , 2012 | ||||||||||||
Pucatherium is an extinct genus of armadillos . It lived from the Middle to the Upper Eocene around 41 to 33 million years ago in central South America . Finds include a partial skeleton and several isolated bone platelets of the armor that emerged in various rock units in northern Argentina . The animals, the size of today's long-nosed armadillos, were characterized by their armor formation, which consisted only of movable bands. Pucatherium probably belongs toa very basal group within the armadillostogether with Lumbreratherium from the same region. The genus was scientifically introduced in 2012. It's kind of recognized.
features
Skeletal features
From Pucatherium , both isolated osteoderms and a partial skeleton have been preserved, comprising the back armor, the tail armor and some postcranial elements. The skull has not yet survived. Based on the findings, a size comparable to the nine-banded armadillo ( Dasypus novemcinctus ) can be assumed for Pucatherium . The spine can be assigned four thoracic, six lumbar, eight sacral and eight tail vertebrae. On the lumbar vertebrae, the typical xenarthric joints were developed as defining features of the secondary articular animals on the lateral processes. The sacrum vertebrae united to form the armadillo-typical synsacrum . An enlarged joint head sat on the humerus , similar to that of the long-nosed armadillos ( Dasypus ) and the bristle armadillos ( Chaetophractus ). In contrast to these, the neck of the joint head was better defined in Pucatherium . The large protrusion towered over the joint head more clearly than in the recent armadillos. The joint neck was also more developed on the femur than in today's species. In addition to the well-trained large and small rolling hills, as with the other armadillos, there was a third rolling hill. It rose a little below the center of the shaft and was thus lower than most recent forms. The tibia and fibula were very robust and short, comparable to today's giant armadillo ( Priodontes ). There were only a few characteristic bony ribs on the shaft of the shin, but the inner ankle was strongly built. The foot is incomplete, but the end phalange of the third ray had a conical extension as a claw support.
Back armor
A back armor, which has largely been preserved in full, had a total of 36 rows of osteoderms or bone platelets. In addition, there are individual isolated parts with four or nine bands. In contrast to today's armadillos, whose carapace consists of a fixed shoulder and pelvic shield with a different number of movable straps in between, the back armor of Pucatherium was composed only of movable straps. The fossil armadillo was thus similar to Lumbreratherium , but differed in turn from other early relatives such as Utaetus , whose armor was only movable in the front area, but rigid in the rear. The osteoderms along the back line increased in size from front to back. They had a square to rectangular shape with lengths of 4.82 to 9.60 mm and widths of 4.07 to 5.52 mm. In general, they were relatively small compared to today's species (the length of an osteoderm in relation to the length of the synsacrum is around 7 to 8% in Pucatherium , but 35% in the bristle armadillos ). Almost half the length of a bone plate was taken up by the articulation surface, which pushes under the osteoderm of the preceding row and thus connects the ligaments with one another. The articulation surface was significantly longer in Pucatherium than in Lumbreratherium . In both forms, however, there were individual pits and humps on the surface - in the former more pronounced than in the latter - which is not the case with most other armadillos. In addition, there were step-like formations on the longitudinal edges, which also represent joint surfaces in contact with neighboring osteoderms. With Pucatherium they moved over the entire longitudinal edge, with Lumbreratherium only over the rear section. The externally visible surface of an osteoderm showed a clear pattern consisting of three longitudinally oriented dents, which were separated by pits and furrows in which there were again small openings (foramina). The central dent was rectangular in shape, the figures on the edge were wider and not divided by additional dimples. The latter is a difference to Lumbreratherium , whose edge pattern was divided into further individual elements. In addition, there were individual patterns on the underside of each osteoderm that are not developed in other armadillos. The osteoderms became smaller towards the side of the shell, but retained their rectangular shape. The typical pattern was directed at an angle here. Small, but partly triangular, bone platelets then appeared on the rear edge. They lacked the typical three-row pattern, and the articulation surface was very short.
In addition to the back armor, parts of the tail armor are still occupied. The osteoderms here largely corresponded to those of the back armor. Their length varied from 6.49 to 7.90 mm, their width from 4.09 to 4.95 mm. In contrast to the long-nosed armadillos, they were not bound into ring structures, but rather distributed irregularly, as in some euphractine armadillos.
Fossil finds
Pucatherium fossil finds have been found from several areas of central South America , especially from northern Argentina . The most important find comes from the Lumbrera Formation in the province of Salta . This is exposed on the east side of the Andes in the Pampa Grande find region and forms part of the parent Salta group . The Lumbrera Formation is divided into a lower and an upper section, both of which contain fossils but are separated by a hiatus . Pucatherium appeared in outcrops along the Río Juramento, exposing the upper range of the rock unit. This is around 124 m thick and consists of coarsely layered dark to light red siltstones and sandy siltstones. In some cases, individual buried soils can be detected in the layers. They go back to a flood plain with vegetation, which developed under temperate climatic conditions with wet and dry annual periods. Radiometric analyzes of zirconium crystals from the upper series of the Lumbrera Formation showed an age of about 39.9 million years, which corresponds to the end of the Middle Eocene . The vertebrate fauna consists mainly of different representatives of ungulates from the group of the Meridiungulata . A skull-less partial skeleton with armor was uncovered from Pucatherium . The lower section of the Lumbrera Formation is more species-rich, as besides the hoofed animals and armadillos, various marsupials and other primitive mammals, as well as crocodiles and lizards, came to light here. A skeleton of Lumbreratherium was also found here as a representative of the armadillos closely related to Pucatherium . It is noticeable that the faunas of the lower and upper Lumbrera Formations do not overlap, which reflects the sedimentological hiatus.
Further remnants of Pucatherium in the form of isolated bone platelets are from the Casa Grande Formation in the Jujuy Province , which borders Salta to the north and west. The Casa Grande Formation is also part of the Salta Group and is around 800 m thick. Mainly it consists of clay and silt stones, which merge into sandstones upwards . The Casa Grande Formation probably originated under similar conditions as the Lumbrera Formation; due to a comparable fauna composition, it also formed in the Middle Eocene. In addition, individual osteoderms from the gesture formation were reported, which extends over the provinces of Catamarca and Salta and connects to the west of the Lumbrera formation. As part of the Pastos-Grandes Group in the Puna region , the more than 600 m thick series of rocks is built up from coarser sediments such as sandstones and conglomerates as the legacy of a once branched river system. The very rich fauna includes various reptiles such as crocodiles, lizards and snakes as well as mammals. Here, too, ungulates dominate, but there is also a diverse fauna of armadillos. From a biostratigraphic point of view, the gesture formation dates to the Middle to Upper Eocene.
Systematics
|
Internal systematics of Dasypoda according to Herrera et al. 2017
|
Pucatherium is an extinct genus from the group of armadillos (Dasypoda). The armadillos living today are assigned to a total of two families , the Dasypodidae with the long-nosed armadillos and the Chlamyphoridae with all other representatives. Characteristic features of the armadillos can be found in the armor on the back with movable straps between two rigid shields and in the pin-like teeth. Both in terms of skeletal anatomy and molecular genetics , the Glyptodontidae , which are also extinct, can also be classified in the armadillos, whose common features include a solid, immobile shell and lobed teeth for ingesting plant-based food. For anatomical reasons, the Pampatheriidae can be placed alongside the Glyptodonts , which outwardly resembled the armadillos. The Dasypoda represent part of the order of the armored secondary articulated animals (Cingulata). Within this order, the Peltephilidae are considered to be a sister group of the Dasypoda for phylogenetic considerations . Pucatherium is at the base of the development of the armadillos. Its closest relative is probably to be found in Lumbreratherium , which has been handed down with a partial skeleton from the Lumbrera Formation in northern Argentina. The close relationship between the two genera shows, among other things, the pronounced humps on the articulation side and on the lower surface as well as the additional lateral articular surfaces of the bone platelets. The latter is known as the "pucatheriines pattern".
The genus Pucatherium was first scientifically described in 2012 by Claudia MR Herrera and research colleagues . The basis for this are individual osteoderms from the Casa Grande formation in the Argentine province of Jujuy (specimen number PVL 6398). The generic name is made up of the Quechua word for "red" and the Greek word θηρίον ( thērion ) for "animal". The former refers to the predominant color of the rock unit in which fossils were enclosed, the latter is a commonly used addition in mammals. P. parvum was the only species named (originally called P. parvus , but corrected to P. parvum in 2016 ). The specific epithet is again of Latin origin and means "small".
literature
- Claudia M. Herrera, Jaime E. Powell and Cecilia Del Papa: Un Nuevo Dasypodidae (Mammalia, Xenarthra) de la Formación Casa Grande (Eoceno) de la Provincia de Jujuy, Argentina. Ameghiniana, 49 (2), 2012, pp. 267-271
- Claudia MR Herrera, Graciela I. Esteban, Martín R. Ciancio and Cecilia Del Papa: New specimen of Pucatherium parvum (Xenarthra, Dasypodidae), a singular dasypodid of the Paleogene (Eocene) of northwest Argentina: importance in the early evolution of armadillos. Journal of Vertebrate Paleontology 39 (4), 2019, p. 1670669, doi: 10.1080 / 02724634.2019.1670669
Individual evidence
- ↑ a b c d e Claudia MR Herrera, Graciela I. Esteban, Martín R. Ciancio and Cecilia Del Papa: New specimen of Pucatherium parvum (Xenarthra, Dasypodidae), a singular dasypodid of the Paleogene (Eocene) of northwest Argentina: importance in the early evolution of armadillos. Journal of Vertebrate Paleontology 39 (4), 2019, p. 1670669, doi: 10.1080 / 02724634.2019.1670669
- ↑ a b c Claudia M. Herrera, Jaime E. Powell and Cecilia Del Papa: Un Nuevo Dasypodidae (Mammalia, Xenarthra) de la Formación Casa Grande (Eoceno) de la Provincia de Jujuy, Argentina. Ameghiniana, 49 (2), 2012, pp. 267-271
- ↑ a b c Martín R. Ciancio, Claudia Herrera, Alejandro Aramayo, Patricio Payrola and María J. Babot: Diversity of cingulate xenarthrans in the middle-late Eocene of Northwestern Argentina. Acta Palaeontologica Polonica 61 (3), 2016, pp. 575-590, doi: 10.4202 / app.00208.2015
- ^ A b Cecilia del Papa, V. García and M. Quattrocchio: Sedimentary facies and palynofacies assemblages in an Eocene perennial lake, Lumbrera formation, northwest Argentina. Journal of South American Earth Sciences 15, 2002, pp. 553-569
- ↑ a b Cecilia del Papa, A. Kirschbaum, J. Powell, A. Brod, F. Hongn and M. Pimentel: Sedimentological, geochemical and paleontological insights applied to continental omission surfaces: A new approach for reconstructing an eocene foreland basin in NW Argentina. Journal of South American Earth Sciences 29, 2010, pp. 327-345
- ↑ a b c d Claudia MR Herrera, Jaime E. Powell, Graciela I. Esteban and Cecilia del Papa: A New Eocene Dasypodid with Caniniforms (Mammalia, Xenarthra, Cingulata) from Northwest Argentina. Journal of Mammalian Evolution 24 (3), 2017, pp. 275-288, doi: 10.1007 / s10914-016-9345-x
- ^ Judith Babot, Daniel A. García López and Timothy J. Gaudin: The Most Ancient Xenarthran Petrosal: Morphology and Evolutionary. Journal of Vertebrate Paleontology 32 (5), 2012, pp. 1186-1197
- ↑ DA García-López and MJ Babot: Notoungulate faunas of north-western Argentina: new findings of early-diverging forms from the Eocene Geste Formation. Journal of Systematic Palaeontology 13 (7), 2015, pp. 557-579, doi: 10.1080 / 14772019.2014.930527
- ↑ Timothy J. Gaudin and John R. Wible: The Phylogeny of Living and Extinct Armadillos (Mammalia, Xenarthra, Cingulata): A Craniodental Analysis. In: MT Carrano, TJ Gaudin, RW Blob and JR Wible (eds.): Amniote Paleobiology. Chicago / London: University of Chicago Press, 2006, pp. 153-198
- ↑ Frédéric Delsuc, Gillian C. Gibb, Melanie Kuch3, Guillaume Billet, Lionel Hautier, John Southon, Jean-Marie Rouillard, Juan Carlos Fernicola, Sergio F. Vizcaíno, Ross DE MacPhee and Hendrik N. Poinar: The phylogenetic affinities of the extinct glyptodonts. 26, 2016, pp. R141-R156
- Jump up ↑ Kieren J. Mitchell, Agustin Scanferla, Esteban Soibelzon, Ricardo Bonini, Javier Ochoa and Alan Cooper: Ancient DNA from the extinct South American giant glyptodont Doedicurus sp. (Xenarthra: Glyptodontidae) reveals that glyptodonts evolved from Eocene armadillos. Molecular Ecology, 25, 2016, pp. 3499-3508, doi: 10.1111 / mec.13695