Английская Википедия:Chichinales Formation

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Шаблон:Short description Шаблон:Infobox rockunit The Chichinales Formation is a geological formation in Río Negro Province, Argentina which dates from the Late Oligocene to the Early Miocene, around 23 to 17.5 million years ago. It predominantly consists of pyroclastic deposits, which were deposited in a semi-arid environment. It is divided up into a number of members. The diverse fauna of the Chichinales Formation, including a variety of turtles and birds, also includes many mammals such as South American native ungulates (notoungulates and litopterns) as well as armadillos, and caviomorph rodents.[1][2]

It is named after the type locality and extends over a large part of the province of Río Negro. It outcrops in the valle de Río Negro, in the towns of General Roca, Río Negro and Villa Regina, bordering the southern bank of the Río Negro. Part of the most important outcrops are located within the Paso Córdova Natural Protected Area.[2]

The Chichinales Formation, broadly speaking, is made up of grayish sandstones, whitish tuffs, siltstones and greenish claystones with paleo soil levels. It is divided into 3 members: lower, middle and upper. The lower one is composed of grayish brown sandstones with low-angle cross bedding, alternating with light brown tuffs, tuffaceous sandstones, sandstones with carbonate cement and shales. In this member, the presence of "opalized" fossil logs is common. The middle member is formed by paleosols and sequences of siltstones, shales and fine sands that in some sectors form lenses in the form of fluvial channels. Finally, the upper member is represented by more homogeneous levels of tuffs, whitish gray tuffites, siltstones, green claystones and tuffaceous sandstones This member, in some sectors, is laterally interdigitated with marginal marine levels of the Gran Bajo del Gualicho Formation, which dates from the Late Oligocene to the Early Pliocene.[3][4] The Chichinales Formation is correlated with the contemporaneous fluvial and lacustrine tuffaceous Collón Curá Formation of the central Neuquén Basin.[5]

The sedimentological and paleontological evidence provided by the Chichinales Formation suggests the existence of open environments with low relief, restricted wooded areas with temporary water bodies and warm temperate climate, in agreement with other Colhuehuapian localities of Chubut Province. In this context, it is possible to interpret, at least tentatively, that the differences between the set of taxa represented in the Cerro Bandera Formation and those of the Chichinales Formation are due to contrasts between the local environmental conditions of each unit rather than to differences in temporal range. It is likely that such differences are the result of the particular conditions that prevailed in the Neuquén region during the Early Miocene, which would be a consequence of its proximity to the Andean zone rather than its latitudinal location.[6]

Paleoflora

Name Species Member/Locality Material Notes Image
Nothofagus[7] N. menendezii

Paleofauna

Reptiles

Lepidosaurs

Name Species Member Material Notes Image
Callopistes[8] C. rionegrensis

Crocodylomorphs

Name Species Member Material Notes Image
Crocodyliformes indet.[9] Currently undescribed Isolated fragment of the posterior region of the skull roof.

Testudines

Name Species Member Material Notes Image
Chelonoidis[10] C. cf. gringorum
Geochelone G. sp.

Birds

Name Species Member Material Notes Image
Charadriiformes indet.[11] Currently undescribed
Opisthodactylus[11] O. horacioperezi
Patagorhacos[11] P. terrificus
Phorusrhacidae indet.[1] Currently undescribed Distal extremity of tibiotarsus

Mammals

Meridiungulates

Name Species Material Notes Image
Cochilius[11] C. volvens An interatheriid
Файл:Cochilius volvens.jpg
Colpodon[1] C. sp. Several maxillary remains
Cramauchenia[1] C. sp. A macraucheniid
Файл:Cramauchenia insolita.jpg
Hegetotheriopsis[12] H. sulcatus A hegetotheriid
Hegetotherium[12][1] H. sp.
Файл:Hegetotherium.svg
Interatheriidae indet. Currently undescribed Mandibular and maxillary fragment
Mesotheriidae indet.[13] Currently undescribed
Proterotheriidae indet.[1] Currently undescribed Maxillary and mandibular fragment
Protypotherium[1] P. sp. An interatheriid
Файл:Protypotherium australe.jpg
Toxodontidae indet.[1] Currently undescribed Left and right mandibular fragments with incomplete series of teeth

Xenarthrans

Name Species Member Material Notes Image
Glyptodontinae indet. Currently undescribed
Proeutatus[1] P. sp. Файл:Reports of the Princeton University Expeditions to Patagonia, 1896-1899 (PLATE XI) (7005553277) (cropped).jpg
Stenotatus[1] cf. S. sp.

Rodents

Name Species Member Material Notes Image
Australoprocta[14] A. fleaglei
Caviocricetus[14] C. lucasi
Echimyidae indet.[1] Currently undescribed
Eoviscaccia[14] E. australis
Octodontoidea indet.[14] Currently undescribed
Willidewu[14][15] W. esteparius

Metatherians

Name Species Member Material Notes Image
Cladosictis[1] C. cf. patagonica Complete right maxillary fragment
Файл:Cladosictis.jpg

References

Шаблон:Reflist

Партнерские ресурсы
Криптовалюты
Магазины
Хостинг
Разное

  1. ↑ 1,00 1,01 1,02 1,03 1,04 1,05 1,06 1,07 1,08 1,09 1,10 1,11 Шаблон:Cite journal
  2. ↑ 2,0 2,1 Шаблон:Cite web
  3. ↑ Шаблон:Cite journal
  4. ↑ Шаблон:Cite journal
  5. ↑ Шаблон:Cite journal
  6. ↑ Шаблон:Cite journal Файл:CC-BY icon.svg Material was copied from this source, which is available under a Creative Commons Attribution 3.0 International License
  7. ↑ Шаблон:Cite journal
  8. ↑ Шаблон:Cite journal
  9. ↑ Шаблон:Cite journal
  10. ↑ Шаблон:Cite journal
  11. ↑ 11,0 11,1 11,2 11,3 Шаблон:Cite journal
  12. ↑ 12,0 12,1 Шаблон:Cite journal
  13. ↑ Шаблон:Cite journal
  14. ↑ 14,0 14,1 14,2 14,3 14,4 Шаблон:Cite book
  15. ↑ Шаблон:Cite journal
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