Pajcha Pata (Cretaceous of Bolivia)

Also known as Pajchapata

Where: Cochabamba, Bolivia (17.9° S, 65.5° W: paleocoordinates 20.4° S, 51.3° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: El Molino Formation, Maastrichtian (72.1 - 66.0 Ma)

• The fossils described in this paper occur about 30 m above the base of the El Molino Formation. This is in the base of the upper part of the Lower Member of the El Molino Formation

•Based on a detailed study of the magnetostratigraphy of the El Molino Formation at the La Palca stratotype section near Potosı́, and applying sequence stratigraphic methods for correlating with the Pajcha Pata section, the fossil bed is ≈68.4 Ma (Sempere et al., 1997, following the time scale of [Cande and Kent, 1992] and [Cande and Kent, 1995]).

• member-level stratigraphic resolution

Environment/lithology: estuary or bay; fine-grained, medium, red, yellow sandstone

• The bed was deposited during a sharp and short regressive phase of the dominantly marine-influenced Lower El Molino at a time when deposition rates for the El Molino were highest. The channel sands derive from a large northeasterly draining river system
• The fossiliferous unit is about 3-m thick, and consists of red to yellow, fine- to medium-grained sandstone.The bed represents a broad channel that can be followed for about 2 km to the northeast of Pajcha Pata.

Size classes: macrofossils, mesofossils

Collected by Marshall, Gayet and Meunier in 1989, 1994

Collection methods: bulk, surface (float), sieve,

• Museo de Historia Natural de Cochabamba, Cochabamba, Bolivia (MHNC) collection

Primary reference: M. Gayet, L. G. Marshall, T. Sempere, F. J. Meunier, H. Capetta and J. Rage. 2001. Middle Maastrichtian vertebrates (fishes, amphibians, dinosaurs and other reptiles, mammals) from Pajcha Pata (Bolivia). Biostratigraphic, palaeoecologic and palaeobiogeographic implications. Palaeogeography, Palaeoclimatology, Palaeoecology 169(1-2):39-68 [R. Benson/R. Benson]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 12855: authorized by Emmanuel Fara, entered by Emmanuel Fara on 20.12.2001, edited by Roger Benson

Creative Commons license: CC BY (attribution)

Taxonomic list

• The fossil remains found at Pajcha Pata are mostly vertebrates. Nevertheless, a small number of invertebrates and plants have been recovered. They are generally very small and poorly preserved. There are gastropods (internal casts that seem identical to those found at Vila Vila21 and Tiupampa28), and Bryozoa. The flora is composed of charophytes. Some fish taxa (Gasteroclupea, Atherinomorpha), already reported at Pajcha Pata ( [Gayet, 1991] and [Gayet et al., 1991]) do not come from the main level but are from the area that includes this locality discussed in this paper. Consequently, they are not discussed in this present work.
? Dryolestoidea "Mammalia gen. et sp. indet. 1"
1 upper right molar: The overall molar morphology is consistent with a tribosphenic mammal, while dryolestoid affinities are suggested
Dagetella sudamericana
isolated scales, neurocranial elements, spines of finlets, and vertebrae
Lepidotyle enigmatica
scales, ?fragments of neurocranial bones, rostrum
Phaerodusichthys taverni
fragments of mandibles, anterior part of a premaxilla
Serrasalminae "indet. 1"
isolated teeth
Serrasalminae "indet. 2"
isolated teeth
Serrasalminae "indet. 3"
isolated teeth
Arioida "new genus"
fragments of dermal cranium and of pectoral and dorsal spines; 'new genus;
Santosius sp.
3 spiny parts of preoperculum
 Sclerorhynchiformes - Sclerorhynchidae
Pucapristis branisi1 Schaffer 1963 elasmobranch
4 oral teeth (Gayet et al 2001)
Ischyrhiza hartenbergeri Cappetta 1975 elasmobranch
22 oral teeth, 10 fragmentary teeth
 Myliobatiformes - Dasyatidae
Dasyatis molinoensis Cappetta 1975 whiptail stingray
three oral teeth
Dasyatis schaefferi Cappetta 1975 whiptail stingray
8 oral teeth
Dasyatis branisai Cappetta 1975 whiptail stingray
4 oral teeth
 Myliobatiformes - Rhombodontidae
Pucabatis hoffstetteri1 Cappetta 1975 stingray
74 oral teeth (Gayet et al 2001)
 Salmoniformes - Enchodontidae
Enchodus sp. Agassiz 1843
isolated teeth
 Teleostei -
 Perciformes - Latidae
Latidae "new genus" perch-like fish
2 fragments of mandible; several vertebra
 Clupeiformes -
 Teleostei -
Siluriformes indet. catfish
fragments of pectoral and dorsal spines
 Siluriformes - Andinichthyidae
Andinichthyidae indet.1 Gayet 1988 catfish
Andinichthys sp. Gayet 1988 catfish
more or less complete pectoral and dorsal spines
 Siluriformes - Siluridae
Rhineastes sp.1 Cope 1872 catfish
 Characiformes -
Characoidei "new genus"
fragment of mandible, isolated lower and/or upper jaws, 'new genus'
 Characiformes - Characidae
Tetragonopterinae indet. Lundberg 1997
numerous isolated teeth
 Osteoglossiformes - Osteoglossidae
Heterotidinae indet. Nelson 1968 arowana
fragments of mandibles, squamules
 Pycnodontiformes - Pycnodontidae
Pycnodontidae indet. Agassiz 1835
numerous teeth
Coelodus toncoensis1
fragments of splenial bones, two vomerian bones, teeth (Gayet et al 2001)
 Lepisosteiformes - Lepisosteidae
Lepisosteus sp.1 Agassiz 1843 gar
isolated scales, 1 vertebra (Gayet et al 2001)
 Dipnoi - Ceratodontidae
Ceratodus sp. Agassiz 1838 lungfish
3 tooth plates
 Gymnophiona -
Gymnophiona indet. Rafinesque 1814 caecilian
7 vertebrae (Gayet et al 2001)
 Salientia -
Anura indet.1 frog
3 presacral vertebrae (Gayet et al 2001)
 Caudata - Urodela
Noterpeton bolivianum n. gen. n. sp.3
Noterpeton bolivianum n. gen. n. sp.3 Rage et al. 1993 siren
 Testudines - Podocnemidae
Podocnemidae indet. sideneck turtle
 Saurischia -
Sauropoda indet. Marsh 1878 sauropod
tooth fragments
 Avetheropoda -
Coelurosauria indet.1 Huene 1914 coelurosaur
1 tooth; numerous tooth fragments
 Loricata -
Crocodylia indet.1 crocodilian
 Squamata - Madtsoiidae
? Madtsoiidae "new genus" Hoffstetter 1961 snake
 Mammalia -
Mammalia "gen. et sp. indet. 2" mammal
1 upper right tooth
 Tribosphenida -
Eutheria sp.2 eutherian
fragment of an upper molar: This specimen is tentatively regarded as a non-tribosphenid therian largely by exclusion from other groups as well as showing clear evidence of cusp structure
 Theriiformes - Dryolestidae
Dryolestidae sp.2 Marsh 1879 mammal
1 upper right molar: The overall molar morphology is consistent with a tribosphenic mammal, while dryolestoid affinities are suggested
 Ceratodontiformes - Lepidosirenidae
Lepidosiren cf. paradoxa1 Fitzinger 1837 South American lungfish
3 pterygoid, 1 prearticular tooth plates
  - Trigonodontidae
Stephanodus minimus
numerous pharyngeal and incisiform teeth