Paleobiota of the Cañadón Asfalto Formation
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The Cañadón Asfalto Formation is a geological formation which dates to the Toarcian age of the Early Jurassic period of Argentina. The rocks of the formation preserve a diverse biota, including plants, dinosaurs, invertebrates, mammals and pterosaurs, among others. The formation is divided into two members: the lower Las Chacritas Member, and the overlying Puesto Almada member, though the latter has also been assigned to the overlying Cañadón Calcáreo Formation by some authors. The members are typically composed of fluvial-lacustrine deposits consisting of sandstones and shales, with a limestone carbonate evaporitic sequence also being present in the lower of the two.
Demospongiae
Color key
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Notes Uncertain or tentative taxa are in small text; |
| Palaeospongillidae reported from the Cañadon Asfalto Formation | ||||||
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| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
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Isolated Specimens |
A freshwater (Lacustrine) member of Palaeospongillidae (Spongillida Sponges). Represents the main lacustrine bottom inhabitant of the Chacritas Paleolake |
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Crustacea
| Crustacea reported from the Cañadon Asfalto Formation | ||||||
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| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
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Isolated Valves |
A freshwater (Lacustrine) member of Eosestheriidae (Spinicaudatan). Originally identified as Cyzicus (Euestheria) taschi. This genus is found in identical alkaline lacustrine settings in the also Toarcian Mawson Formation of Antarctica |
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Isolated Valves |
A freshwater (Lacustrine) member of Afrograptidae (Spinicaudatan). Given the stratigraphic uncertainty, it may come from the Cañadón Calcáreo Formation. |
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Isolated Valves |
A freshwater (Lacustrine) member of Darwinulidae (Ostracod). |
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Isolated Valves |
A freshwater (Lacustrine) member of Palaeolimnadiopseidae (Spinicaudatan). |
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Isolated Valves |
A freshwater (Lacustrine) member of Euestheriidae (Spinicaudatan). |
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Isolated Valves |
A freshwater (Lacustrine) member of Fushunograptidae (Spinicaudatan). |
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Isolated Valves |
A freshwater (Lacustrine) member of Limnocytheridae (Ostracodan). Given the stratigraphic uncertainty, it may come from the Cañadón Calcáreo Formation |
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Isolated Valves |
A freshwater (Lacustrine) member of Loxoconchidae (Ostracodan). Given the stratigraphic uncertainty, it may come from the Cañadón Calcáreo Formation. |
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Isolated Valves |
A freshwater (Lacustrine) member of Darwinulidae (Ostracodan). These species are characteristic of the Middle Jurassic of northern China and where used to correlate the age of the beds |
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Isolated Valves |
A freshwater (Lacustrine) member of Antronestheriidae (Spinicaudatan). Given the stratigraphic uncertainty, it may come from the Cañadón Calcáreo Formation. |
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Isolated Valves |
A freshwater (Lacustrine) member of Cytheroidea (Ostracodan). Given the stratigraphic uncertainty, it may come from the Cañadón Calcáreo Formation. |
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Isolated Valves |
A freshwater (Lacustrine) member of Limnocytheridae (Ostracodan). Given the stratigraphic uncertainty, it may come from the Cañadón Calcáreo Formation. |
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Isolated Valves |
A freshwater (Lacustrine) member of Fushunograptidae (Spinicaudatan). |
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Mollusca
| Mollusca reported from the Cañadon Asfalto Formation | ||||||
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| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
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Isolated Shells |
A freshwater (Lacustrine) member of Corbiculidae (Bivalve). |
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Isolated Shells |
A freshwater (Lacustrine) member of Corbiculidae (Bivalve). |
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Isolated Shells |
A freshwater (Lacustrine) member of Unionidae (Bivalve). The most abundant Bivalve genus on the Formation. Represents also some of the smallest-sized specimens recorded in the Mesozoic, what can be explained by potential environment stress.[12] |
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Indeterminate |
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Isolated Shells |
A freshwater (Lacustrine) member of Unionidae (Bivalve). |
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Isolated Shells |
A freshwater (Lacustrine) member of Palaeomutelidae (Bivalve). |
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Isolated Shells |
A freshwater (Lacustrine) member of Tateidae (Snail). |
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Indeterminate |
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Isolated Shells |
A freshwater (Lacustrine) member of Sphaeriida (Bivalve). |
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Isolated Shells |
A freshwater (Lacustrine) member of Viviparidae (Snail). |
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Insecta
Insect eggs of unknown affinity were reported from several layers of the Estancia Fossati locality.[1]
| Insects reported from the Cañadon Asfalto Formation | ||||||
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| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
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Indeterminate |
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Head capsules |
Indeterminate Bittacidae (Migdes) remains, associated with lacustrine facies. Given the stratigraphic uncertainty, it may come from the Cañadón Calcáreo Formation |
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Indeterminate |
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Elytra and body remains |
Indeterminate Beetle remains, associated with lacustrine facies |
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C. isp. |
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Imprints or compressed moulds of larval cases |
Indeterminate Trichoptera (Caddisflies) Ichnofossils, associated with lacustrine facies. Larval cases made of conchostracan shells |
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Indeterminate |
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Fragmentary wings |
Indeterminate Heteroptera remains, associated with lacustrine facies |
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Indeterminate |
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Wings and parts of body |
Indeterminate Bittacidae (Scorpionfly) remains, associated with lacustrine facies. Given the stratigraphic uncertainty, it may come from the Cañadón Calcáreo Formation |
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O. isp. |
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Imprints or compressed moulds of larval cases |
Indeterminate Trichoptera (Caddisflies) Ichnofossils, associated with lacustrine facies. Larval cases made of ostracodan shells |
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T. isp. |
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Imprints or compressed moulds of larval cases |
Indeterminate Trichoptera (Caddisflies) Ichnofossils, associated with lacustrine facies. Larval cases made of clasts or terrigenous particles |
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Indeterminate |
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Wings and larval cases |
Indeterminate Trichoptera (Caddisflies) remains, associated with lacustrine facies |
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Vertebrates
Fish
| Actinopteri reported from the Cañadon Asfalto Formation | ||||||
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| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
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Indeterminate |
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Isolated large median fin & Isolated Scales |
A freshwater (Lacustrine) member of Archaeomaenidae (Teleostei). Maybe related to the genus Oreochima, coming from layers coeval, coregional, and of identical deposition of the Mawson Formation of Antarctica |
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Amphibians
| Amphibians reported from the Cañadon Asfalto Formation | ||||||
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| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
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Las Chacritas Member |
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An early frog of the family Notobatrachidae. Notobatrachus degiustoi can be distinguished from N. reigsi by features of the skull. The presence of this anuran in several locations suggests local proliferation linked with lacustrine bodies |
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Turtles
| Turtles reported from the Cañadon Asfalto Formation | ||||||
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| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
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Las Chacritas Member |
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A stem turtle (Mesochelydian) outside both extant groups, closely related with Kayentachelys aprix of North America and Indochelys spatulata of India. Likely occupied aquatic or semiaquatic niches.[23] |
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Indeterminate |
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Las Chacritas Member |
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Indeterminate Turtle remains |
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Lepidosaurs
| Lepidosaurs reported from the Cañadon Asfalto Formation | ||||||
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| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Sphenocondor[25] |
S. gracilis |
Queso Rallado |
Las Chacritas Member |
Dentary |
A Sphenodontian Rhynchocephalian, closely related with Godavarisaurus from the almost coeval Jurassic Kota Formation of India, maybe part of an endemic Gondwanan clade.[25] |
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Crocodylomorpha
| Crocodyliformes reported from the Cañadón Asfalto Formation | ||||||
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| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
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Indeterminate |
Queso Rallado |
Las Chacritas Member |
Teeth & several isolated remains |
Indeterminate crocodylomorph remains that represent small carnivorous vertebrates linked with lacustrine facies. |
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Pterosaurs
| Pterosaurs reported from the Cañadón Asfalto Formation | ||||||
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| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
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A. koi |
Canadón Carrizal |
Las Chacritas Member |
A braincase, as well as a mandible and cervical vertebrae. |
A pterosaur either related with Breviquartossa or maybe even a sister group of monofenestratan (Wukongopteridae + Pterodactyloidea) pterosaurs |
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| Ctenochasmatidae?[29] | Indeterminate | Queso Rallado | Not Determined | Isolated tooth | Resembles the teeth of Pterodaustro. The exact provenance of the specimen is unknown | |
| Melkamter[29] | M. pateko | Queso Rallado | Las Chacritas Member | Partial skull and associated postcranial elements | A monofenestratan pterosaur, representing the oldest known record of this clade | |
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Indeterminate |
Las Chacritas |
Las Chacritas Member |
Uncatalogued specimens, several mandibles, braincase, shoulder girdle, two humeri, several wing-finger phalanges |
Indeterminate remains of a pterosaur, possibly a rhamphorhynchoid with a wingspan of about 1.5–2 metres (4.9–6.6 ft). The mandible morphology is similar to scaphognathines.[31] |
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Dinosaurs
Theropods
During a campaign conducted in early 2021, remains of a large theropod dinosaur were found near the town of Las Chacritas. In 2020 a new fossil locality was found, named Cañadón de las Huellas, due to the large number of sauropods, and probably theropods, footprints on one of the canyon walls. In the same locality in 2021, articulated remains were recovered and represent at least one sauropod and one large theropod.[32] At least four theropod morphotypes, including one with ceratosaur and another with Piatnitzkysauridae affinities, are known from the Cañadón Bagual.[33]
| Theropoda reported from the Cañadón Asfalto Formation | ||||||
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| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
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A. vialidadi |
Cerro Condor |
Las Chacritas Member |
Nearly compete skull and largely complete front half of the skeleton forward of the hips, distal pubis and fermur and proximal fibula and tibia, partial foot |
A probable early member of Allosauroidea |
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Indeterminate |
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Las Chacritas Member |
Isolated teeth: MPEF BA 182/08, BA 40/08, BA 09/80, BA 88/08, BA 252G+165/08 A, BA 252G+165/08 B, BA 252G+165/08 C |
Theropod dinosaur teeth that resemble those assigned to the families Ceratosauridae, Megalosauridae and Abelisauridae |
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Indeterminate |
Cañadon Bagual |
Las Chacritas Member |
A dentary with teeth in situ, MPEF-PV 6775 |
It resembles the dentary of Ceratosaurus |
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C. currumili |
Las Chacritas |
Las Chacritas Member |
Partial articulated skeleton |
A relative of Piatnitzkysaurus from the same formation, and a possible junior synonym of it as well. |
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Indeterminate |
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Las Chacritas Member |
Isolated Teeth: MEPF BA 61/08, BA 103/08, BA 32/08 A, BA 32/08 B, BA 104/08, BA 226B/08, PV 3498, BA 29/08, BA51/08, BA 270/08 a, BA 270/08 b, BA 270/08 c |
Theropod dinosaur teeth that resemble those assigned to the family Dromaeosauridae. Alternatively, they could belong to basal members of Coelurosauria |
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E. mefi |
Jugo Luco |
Las Chacritas Member |
A nearly complete articulated skeleton |
A Neoceratosaur, which was suggested to be a basal member of Abelisauria, but also a member of Ceratosauridae |
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Indeterminate |
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Las Chacritas Member |
Isolated Teeth: MPEF PV 1175, BA 66/08, PV 1356, PV 1357 |
Theropod dinosaur teeth that resemble those assigned to the family Megalosauridae. |
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Indeterminate |
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Las Chacritas Member |
Isolated Teeth: MPEF BA 68/08, BA 92/08, PV 3499, BA 68/08, BA 183/08 |
Theropod dinosaur teeth that resemble those assigned to basal neotheropods, such as members of Coelophysoidea. |
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Indeterminate |
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Las Chacritas Member |
Isolated Teeth & Cranial remains: MPEF 1717 CC 205, PV 3440A A, PV 3440A B, PV 3440A C, PV 3440A D, PV 3440A E, PV 3440A F, PV 3440A G |
Theropod dinosaur teeth that resemble those assigned to members of Piatnitzkysauridae. | ||
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P. floresi |
Cerro Cóndor South |
Las Chacritas Member |
Two "fragmentary skulls with associated postcranium."[41] |
Possible senior synonym of Condorraptor from the same formation. |
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Indeterminate |
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Las Chacritas Member |
Isolated Teeth : MEPF PV 1350 |
Theropod dinosaur teeth resembling those assigned to members of Spinosauridae. Alternatively, they could belong to members of Ceratosauria |
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Indeterminate |
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Las Chacritas Member |
Isolated Teeth : MEPF BA 84/08, BA 49/08 A, BA 49/08 B, BA 64/08, BA 65/08, BA 266/07 |
Theropod dinosaur teeth that resemble with those assigned to members of Megalosauridae and Dromaeosauridae |
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Indeterminate |
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Las Chacritas Member |
Isolated Teeth : MPEF PV 1640 |
"Outlier" tooth that doesn't fit in any previously known morphotype, maybe due to preservation |
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Indeterminate |
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Las Chacritas Member |
Footprints |
Possible theropod footprints, unassigned to any concrete ichnogenus |
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Sauropodomorphs
A sediment tubular shaped mass enriched in organic matter, closely associated within the ventral area of articulated remains of a sauropod, was recovered at Cerro Condor, composed of a high concentration of pollen grains & cuticular fragments, mainly leaves of two morphotypes (Araucariaceae and Cheirolepidiaceae), probably representing the gut contents of the sauropod, inferring a conifer-based diet.[43]
| Sauropodiformes reported from the Cañadón Asfalto Formation | ||||||
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| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
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B. alba |
Cañadon Bagual |
Las Chacritas Member |
The partial skeletons of three individuals |
An early member of Eusauropoda, related with the African genus Spinophorosaurus |
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Indeterminate |
Cerro Condor Sur |
Las Chacritas Member |
MACN-CH 934: axial neural arches and spines, an ilium, a pubis, ?two or ?three ischia, and two maxillae |
This specimen shows strong Diplodocidae affinities, yet it has been considered either a derived non-neosauropodan eusauropod (having resemblance with Lapparentosaurus in some characters) or even a basal neosauropod (also resembling Haplocanthosaurus) |
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Indeterminate |
Cerro Condor Sur |
Las Chacritas Member |
MACN-CH 230: three dorsal vertebrae |
Likely a eusauropod, possibly a cetiosaurid. Smaller than other sauropod taxa found in the formation. |
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| Eusauropoda?[47] | Indeterminate | Cerro Condor Este | Las Chacritas Member | MPEF-PV 12010: A left premaxilla | It has the thickest enamel of the sampled sauropod specimens | |
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P. fariasi |
Cerro Condor |
Las Chacritas Member |
Many specimens, including a partial skull. |
A non-neosauropodan eusauropodan member of Cetiosauridae. This genus represents the most abundant sauropod in the formation |
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Indeterminate |
Queso Rallado, near Cerro Cóndor |
Las Chacritas Member |
Isolated Teeth: MPEF-PV 10860 |
An indeterminate Sauropodiform or a very basal sauropod or even dental material of Volkheimeria.[50] |
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Indeterminate |
Cerro Condor Sur |
Las Chacritas Member |
MACN-CH 219, 223(+221), 231 |
Too fragmentary to be ascribed to any taxon, currently classified as Sauropoda indet. |
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Indeterminate |
Queso Rallado, near Cerro Cóndor |
Las Chacritas Member |
Isolated Teeth: MPEF-PV 10606 |
An indeterminate Titanosauriform. It can be alternatively a basal Eusauropod. Possible relationships with Atlasaurus |
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V. chubutensis |
Cerro Cóndor South |
Las Chacritas Member |
"Partial skeleton consisting of presacral and sacral vertebrae, pelvis, [and] hindlimb." |
Either a gravisaur or a sister taxon of the Indian genus Barapasaurus |
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Ornithischians
| Ornithischians reported from the Cañadón Asfalto Formation | ||||||
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| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
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Indeterminate |
Queso Rallado |
Las Chacritas Member |
Isolated ungual phalanx and Isolated Teeth: MPEF-PV 3818, MPEF-PV 3824, MEPF-PV 3820, MEPF-PV 3825, MEPF-PV 10861, MPEF-PV 10823, MPEF-PV 3821 & MPEF-PV 10864 |
An indeterminate Cerapodan with resemblances with Hypsilophodon. Some of the referred remains have been reclassified as Manidens material |
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Indeterminate |
Queso Rallado |
Las Chacritas Member |
Metapodials, caudal vertebrae, and isolated phalanges: MPEF-PV 3826 |
heterodontosaurid that cannot be compared with Manidens due to the lack of overlapping fossils. |
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M. condorensis |
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Las Chacritas Member |
Partial articulated specimen, skull & associated elements as well referred isolated teeth: MPEF-PV 3809, MPEF-PV 3211, MPEF-PV 3808, MPEF-PV 10867, MPEF-PV 1719, MPEF-PV 1786, MPEF-PV 1718, MPEF-PV 3810, MPEF-PV 3811, MPEF-PV 3812, MPEF-PV 3813, MPEF-PV 3814, MPEF-PV 3815, MPEF-PV 3816, MPEF-PV 10866 |
A primitive and small heterodontosaurid. Fossils attributed to this genus may have been at least partially arboreal. Principal component analysis found that the feet of Manidens were most similar to those of tree-perching birds.[54] |
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Indeterminate |
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Las Chacritas Member |
Isolated teeth: MPEF-PV 3817, MPEFPV 3819, MPEF-PV 3822. |
Not referable to any taxa beyond Ornithischia Indet. |
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Mammals
| Mammals reported from the Cañadón Asfalto Formation | ||||||
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| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
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Indeterminate |
Queso Rallado |
Las Chacritas Member |
Isolated Teeth |
An Allotherian whose affinities hasn't been tested |
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A. fariasorum |
Queso Rallado |
Las Chacritas Member |
MPEF-PV2362, fragmentary left maxilla, MPEF-PV2363 partial skeleton, MPEFPV2364 isolated complete right upper last molariform |
A volaticotherian (Alticonodontinae), closely related to the Asian genus Volaticotherium, having similar postcraneal appearance, indicating possible gliding capabilities, yet better material is needed to prove it.[56] |
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A. patagonicus |
Queso Rallado |
Las Chacritas Member |
MPEF PV 1671, complete lower maxilla |
An Australosphenidan, related to Henosferus in Henosferidae. |
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C. spanios |
Queso Rallado |
Las Chacritas Member |
MPEF-PV 2365, isolated complete lower left molariform |
An "amphilestid" triconodont, related with the late jurassic African Tendagurodon.[55] |
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Las Chacritas Member |
MPEF 2353 right lower jaw, MPEF 2354 Left lower jaw, MPEF 2357 Left lower jaw, referred MPEF 2355 isolated upper premolar |
An Australosphenidan, related to Asfaltomylos in Henosferidae, being twice as large as this last one.[58] |
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Fungi
| Genus | Species | Location | Stratigraphic position | Member | Material | Ecogroup | Palaeoclimate requirements | Notes |
|---|---|---|---|---|---|---|---|---|
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Central Patagonia |
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Hypae and Miospores |
Unknown: either Aquatic (Freshwater) or Parasitic |
Unknown, suggested highly seasonality |
A Fungus of uncertain relationships. This species is recovered in both coal seams and proximal prodelta sediments, making the assignation of a biome complex.[59] | |
























