Cañadón Asfalto Formation

The Cañadón Asfalto Formation is a Middle Jurassic to Late Jurassic geologic formation, from the Jurassic period of the Mesozoic Era. Its age is controversial, uranium-lead dating of the volcanic tuff beds having given various different ages.[1] Recent work suggests that the base of the formation was formed around 171 Ma, during the upper Aalenian, while the main age for the Lower Las Chacritas Member being around 168 Ma, during the Bajocian, Bathonian and Callovian While the overlying Puesto Almada Member seems to be around 158 ma, or Oxfordian age.[2]

Cañadón Asfalto Formation Stratigraphic range: Late Aalenian-Oxfordian ~171–158 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Cañadón Asfalto Formation near Cerro Cóndor, Chubut, Argentina
Type	Geological formation
Unit of	Sierra de Olte Group
Sub-units	Las Chacritas Member, Puesto Almada Member
Underlies	Cañadón Calcáreo Formation
Overlies	Lonco Trapial Formation
Thickness	600 m (2,000 ft)
Lithology
Primary	Sandstone
Other	Limestone, shale, conglomerate, tuffite
Location
Coordinates	43.4°S 69.2°W
Approximate paleocoordinates	40.5°S 29.3°W
Region	Chubut Province, Patagonia
Country	Argentina
Extent	Cañadón Asfalto Basin
Formation map and location, shaded horizontally

It is located in the Cañadón Asfalto Basin, a rift basin in Chubut Province of northwestern Patagonia, in southern Argentina.[3] The basin started forming in the earliest Jurassic.[4]

It is composed of fluvial-lacustrine deposits, typically sandstones and shales with a saline paleolake carbonate evaporitic sequence of limestone in its lowest Las Chacritas Member.[3][5] Interbedded with these are volcanic tuffites. It is divided into two members, the Las Chacritas Member, and the overlying Puesto Almada member, but the latter has also been assigned to the overlying Cañadón Calcáreo Formation by other authors.[6]

According to a palynological study the dominant pollen was produced by the conifer families Cheirolepidiaceae (Classopollis) and Araucariaceae (mainly Araucariacites and Callialasporites), suggesting that warm-temperate and relatively humid conditions under highly seasonal climate prevailed during the depositional times of the unit. The abundance of Botryococcus supports the presence of a shallow lake with probably saline conditions.[7]

Vertebrate fauna

Amphibians

Amphibians reported from the Cañadon Asfalto Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Notobatrachus	N. degiustoi	Cañadon Bagual	Las Chacritas Member	Many articulated, mostly complete skeletons.[8]	Can be distinguished from N. reigsi by features of the skull.
	N. reigi	Cañadon Bagual	Las Chacritas Member	Most of a partially articulated skeleton and skull.[8]	Can be distinguished from N. degiustoi by features of the skull.

Turtles

Turtles reported from the Cañadon Asfalto Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Condorchelys	C. antiqua	Queso Rallado	Las Chacritas Member	Most of a skull, carapace, and plastron.[8]	A stem turtle outside both extant groups.

Lepidosaurs

Lepidosaurs reported from the Cañadon Asfalto Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Sphenocondor	S. gracilis	Queso Rallado	Las Chacritas Member	Dentary[9]	Rhynchocephalian

Pterosaurs

Pterosaurs reported from the Cañadón Asfalto Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Allkaruen	A. koi	Canadón Carrizal	Las Chacritas Member	A braincase, as well as a mandible and cervical vertebrae.[10]

Crocodyliformes

Crocodyliformes reported from the Cañadón Asfalto Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Almadasuchus	A. figarii	Puesto Almada	Puesto Almada Member	"posterior half of the skull, further isolated elements of skull and lower jaws, fragmentary postcranium"[11]

Dinosaurs

Dinosaurs reported from the Cañadón Asfalto Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Asfaltovenator	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 fibia and tibia, partial foot	A probable early member of Allosauroidea.[12]
Bagualia	B. alba	Cañadon Bagual	Las Chacritas Member		A early member of Eusauropoda.
Condorraptor	C. currumili	Las Chacritas	Las Chacritas Member	Partial articulated skeleton.[13]	A relative of Piatnitzkysaurus from the same formation, and a possible junior synonym of it as well.[14]
Eoabelisaurus	E. mefi	Jugo Luco	Las Chacritas Member	A nearly complete articulated skeleton.[15]	A primitive abelisaurian about 6 to 6.5 m (20 to 21 ft) long.
Manidens	M. condorensis	Queso Rallado	Las Chacritas Member	Partial articulated specimen.[16]	A primitive and small heterodontosaurid.
Patagosaurus	P. fariasi	Cerro Condor	Las Chacritas Member	Many specimens, including a partial skull.[17]	A non-neosauropodan eusauropodan, one of three from the formation.
Piatnitzkysaurus	P. floresi	Cerro Cóndor South	Las Chacritas Member	Two "fragmentary skulls with associated postcranium."[18]	Possible senior synonym of Condorraptor from the same formation.[14]
Volkheimeria	V. chubutensis	Cerro Cóndor South	Las Chacritas Member	"Partial skeleton consisting of presacral and sacral vertebrae, pelvis, [and] hindlimb."[19]	A non-neosauropodan eusauropodan.

Mammals

Mammals reported from the Cañadón Asfalto Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Argentoconodon	A. fariasorum	Queso Rallado	Las Chacritas Member	Jaws and several post-cranial elements.[20]	A volaticotherian.
Asfaltomylos	A. patagonicus	Queso Rallado	Las Chacritas Member	Dental remains.[8]	Related to Henosferus in Henosferidae.
Henosferus	H. molus	Queso Rallado	Las Chacritas Member	Dental remains.[8]	Related to Asfaltomylos in Henosferidae.
Condorodon	C. spanios	Queso Rallado	Las Chacritas Member	Dental remains.	An "amphilestid".[21]

Plant remains

Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Baculatisporites	B. comaumensis	Central Patagonia	Cañadon Lahuincó	Spores.[22]	Spores from the family Osmundaceae.
Dictyophyllidites	D. sp.	Central Patagonia	Cañadon Lahuincó	Spores.[22]	Spores of the family Osmundaceae.
Nevesisporites	N. cf. radiatus	Central Patagonia	Cañadon Lahuincó	Spores.[22]	Spores of the group Bryophyta.
cf. Rugulatisporites	cf. R. sp.	Central Patagonia	Cañadon Lahuincó	Spores.[22]	Spores of the family Osmundaceae.
Alisporites	A. similis	Central Patagonia	Cañadon Lahuincó	Pollen.[22]	Pollen of the family Caytoniaceae.
	A. sp.	Central Patagonia	Cañadon Lahuincó	Pollen.[22]	Pollen of the family Caytoniaceae.
Araucariacites	A. australis	Central Patagonia	Cañadon Lahuincó	Pollen.[22]	Pollen of the family Araucariaceae.
	A. fissus	Central Patagonia	Cañadon Lahuincó	Pollen.[22]	Pollen of the family Araucariaceae.
Callialasporites	C. dampieri	Central Patagonia	Cañadon Lahuincó	Pollen.[22]	Pollen of the family Araucariaceae.
	C. microvelatus	Central Patagonia	Cañadon Lahuincó	Pollen.[22]	Pollen of the family Araucariaceae.
	C. turbatus	Central Patagonia	Cañadon Lahuincó	Pollen.[22]	Pollen of the family Araucariaceae.
Cerebropollenites	C. macroverrucosus	Central Patagonia	Cañadon Lahuincó	Pollen.[22]	Pollen of the family Taxodiaceae.
Classopollis	C. classoides	Central Patagonia	Cañadon Lahuincó	Pollen.[22]	Pollen of the family Cheirolepidiaceae.
	C. intrareticulatus	Central Patagonia	Cañadon Lahuincó	Pollen.[22]	Pollen of the family Cheirolepidiaceae.
	C. simplex	Central Patagonia	Cañadon Lahuincó	Pollen.[22]	Pollen of the family Cheirolepidiaceae.
Exesipollenites	E. sp.	Central Patagonia	Cañadon Lahuincó	Pollen.[22]	Pollen of the family Cheirolepidiaceae.
Perinopollenites	P. elatoides	Central Patagonia	Cañadon Lahuincó	Pollen.[22]	Pollen of the family Podocarpaceae.
Phrixipollenites	P. sp.	Central Patagonia	Cañadon Lahuincó	Pollen.[22]	Pollen of the family Podocarpaceae.
Podocarpadites	P. verrucosus	Central Patagonia	Cañadon Lahuincó	Pollen.[22]	Pollen of the family Podocarpaceae.
	P. sp.	Central Patagonia	Cañadon Lahuincó	Pollen.[22]	Pollen of the family Podocarpaceae.
Microcachryidites	M. castellanosii	Central Patagonia	Cañadon Lahuincó	Pollen.[22]	Pollen of the family Podocarpaceae.
Botryococcus	B. sp.	Central Patagonia	Cañadon Lahuincó	Algae.[22]	Algae of the family Botryococcaceae.
Ovoidites	O. spp.	Central Patagonia	Cañadon Lahuincó	Algae.[22]	Algae of the family Zygnemataceae.
Leiosphaeridia	L. sp.	Central Patagonia	Cañadon Lahuincó	Algae.[22]	Algae of the family Prasinophyceae.
Equisetites	E. approximatus	Central Patagonia	Cañadon Lahuincó	Plants.[22]	Plants of the group Equisetales.
Cladophlebis	C. grahami	Central Patagonia	Cañadon Lahuincó	Plants.[22]	Plants of the family Osmundaceae.
Sphenopteris	S. patagonica	Central Patagonia	Cañadon Lahuincó	Plants.[22]	Plants of the group Filicales.
	S. hallei	Central Patagonia	Cañadon Lahuincó	Plants.[22]	Plants of the group Filicales.
Scleropteris	S. furcata	Central Patagonia	Cañadon Lahuincó	Plants.[22]	Plants of the group Pteridospermata.
Araucaritites	A. chuchensis	Central Patagonia	Cañadon Lahuincó	Plants.[22]	Plants of the family Araucariaceae.
Pagiophyllum	P. divaricatum	Central Patagonia	Cañadon Lahuincó	Plants.[22]	Plants of the family Araucariaceae.
	P. fiestmantelli	Central Patagonia	Cañadon Lahuincó	Plants.[22]	Plants of the family Araucariaceae.
Elatoclaudus	E. conferta	Central Patagonia	Cañadon Lahuincó	Plants.[22]	Plants of the family Podocarpaceae.
	E. jabalpurensis	Central Patagonia	Cañadon Lahincó	Plants.[22]	Plants of the family Podocarpaceae.
Athrotaxis	A. ungeri	Central Patagonia	Cañadon Lahuincó	Plants.[22]	Plants of the family Taxodiaceae.

See also

• List of dinosaur-bearing rock formations
• Chon Aike Formation
• La Matilde Formation

References

1. Cúneo, Rubén; Ramezani, Jahandar; Scasso, Roberto; Pol, Diego; Escapa, Ignacio; Zavattieri, Ana M.; Bowring, Samuel A. (November 2013). "High-precision U–Pb geochronology and a new chronostratigraphy for the Cañadón Asfalto Basin, Chubut, central Patagonia: Implications for terrestrial faunal and floral evolution in Jurassic". Gondwana Research. 24 (3–4): 1267–1275. Bibcode:2013GondR..24.1267C. doi:10.1016/j.gr.2013.01.010. ISSN 1342-937X.
2. Hauser, N.; Cabaleri, N.G.; Gallego, O.F.; Monferran, M.D.; Silva Nieto, D.; Armella, C.; Matteini, M.; Aparicio González, P.A.; Pimentel, M.M.; Volkheimer, W.; Reimold, W.U. (October 2017). "U-Pb and Lu-Hf zircon geochronology of the Cañadón Asfalto Basin, Chubut, Argentina: Implications for the magmatic evolution in central Patagonia". Journal of South American Earth Sciences. 78: 190–212. doi:10.1016/j.jsames.2017.05.001. hdl:11336/36240.
3. Cabaleri, Nora G.; Benavente, Cecilia A. (2013). "Sedimentology and paleoenvironments of the Las Chacritas carbonate paleolake, Cañadón Asfalto Formation (Jurassic), Patagonia, Argentina". Sedimentary Geology. 284–285: 91–105. Bibcode:2013SedG..284...91C. doi:10.1016/j.sedgeo.2012.11.008.
4. Figari et al., 2015, p.142
5. Researchgate.net: "The palynology of the Cañadón Asfalto Formation (Jurassic), Cerro Cóndor depocentre, Cañadón Asfalto Basin, Patagonia, Argentina: Palaeoecology and palaeoclimate based on ecogroup analysis"
6. Rauhut, Oliver W. M.; Pol, Diego (November 2017). "A Theropod Dinosaur from the Late Jurassic Cañadón Calcáreo Formation of Central Patagonia, and the Evolution of the Theropod Tarsus". Ameghiniana. 54 (5): 539–566. doi:10.5710/amgh.12.10.2017.3105. ISSN 0002-7014. S2CID 134945437.
7. Olivera, Daniela; Zavattieri, Ana; Quattrocchio, Mirta (2015-03-11). The palynology of the Cañadón Asfalto Formation (Jurassic), Cerro Cóndor depocentre, Cañadón Asfalto Basin, Patagonia, Argentina: Palaeoecology and palaeoclimate based on ecogroup analysis. 39.
8. Escapa, I.H.; Sterli, J.; Pol, D.; Nicoli, L. (2008). "Jurassic Tetrapods and Flora of Cañadon Asfalto Formation in Cerro Cóndor Area, Chubut Province" (PDF). Revista de la Asociación Geológica Argentina. 63 (4): 613–624. Archived from the original (PDF) on 2014-09-24. Retrieved 2014-09-17.
9. Apesteguía, S. N.; Gómez, R. L. O.; Rougier, G. W. (2012). "A basal sphenodontian (Lepidosauria) from the Jurassic of Patagonia: New insights on the phylogeny and biogeography of Gondwanan rhynchocephalians". Zoological Journal of the Linnean Society. 166 (2): 342. doi:10.1111/j.1096-3642.2012.00837.x.
10. Codorniú, L.; Carabajal, A.P.; Pol, D.; Unwin, D.; Rauhut, O.W.M (2016). "A Jurassic pterosaur from Patagonia and the origin of the pterodactyloid neurocranium". PeerJ. 4: e2311. doi:10.7717/peerj.2311. PMC 5012331. PMID 27635315.
11. Pol, D.; Rauhut, O. W. M.; Lecuona, A.; Leardi, J. M.; Xu, X.; Clark, J. M. (2013). "A new fossil from the Jurassic of Patagonia reveals the early basicranial evolution and the origins of Crocodyliformes". Biological Reviews. 88 (4): 862–872. doi:10.1111/brv.12030. PMID 23445256. S2CID 14648168.
12. Oliver W. M. Rauhut; Diego Pol (2019). "Probable basal allosauroid from the early Middle Jurassic Cañadón Asfalto Formation of Argentina highlights phylogenetic uncertainty in tetanuran theropod dinosaurs". Scientific Reports. 9 (1): Article number 18826. doi:10.1038/s41598-019-53672-7. PMC 6906444. PMID 31827108.
13. Rauhut, O.W.M. (2005). "Osteology and relationships of a new theropod dinosaur from the Middle Jurassic of Patagonia". Palaeontology. 48 (1): 87–110. doi:10.1111/j.1475-4983.2004.00436.x.
14. Novas, Fernando (2009). The Age of Dinosaurs in South America. Indiana University Press. p. 118. ISBN 978-0253352897.
15. Diego Pol & Oliver W. M. Rauhut (2012). "A Middle Jurassic abelisaurid from Patagonia and the early diversification of theropod dinosaurs". Proceedings of the Royal Society B: Biological Sciences. 279 (1804): 3170–5. doi:10.1098/rspb.2012.0660. PMC 3385738. PMID 22628475.
16. Pol, D.; Rauhut, O.W.M.; Becerra, M. (2011). "A Middle Jurassic heterodontosaurid dinosaur from Patagonia and the evolution of heterodontosaurids". Naturwissenschaften. 98 (5): 369–379. Bibcode:2011NW.....98..369P. doi:10.1007/s00114-011-0780-5. PMID 21452054. S2CID 22636871.
17. Rahut, O.W.M. (2003). "A Dentary of Patagosaurus (Sauropoda) from the Middle Jurassic of Patagonia". Ameghiniana. 40 (3): 425–432. ISSN 0002-7014.
18. "Table 4.1," in Weishampel, et al. (2004). Page 72.
19. "Table 13.1," in Weishampel, et al. (2004). Page 262.
20. Gaetano, L.C.; Rougier, G.W. (2011). "New materials of Argentoconodon fariasorum (Mammaliaformes, Triconodontidae) from the Jurassic of Argentina and its bearing on triconodont phylogeny". Journal of Vertebrate Paleontology. 31 (4): 829–843. doi:10.1080/02724634.2011.589877. S2CID 85069761.
21. L. C. Gaetano and G. W. Rougier. 2012. First amphilestid from South America: a molariform from the Jurassic Cañadón Asfalto Formation, Patagonia, Argentina. Journal of Mammalian Evolution
22. Volkheimer, W.; Quattrocchio, M.; Cabaleri, N.; García, V. (2011). "Palynology and paleoenvironment of the Jurassic lacustrine Cañadón Asfalto Formation at Cañadón Lahuincó locality, Chubut Province, Central Patagonia, Argentina". Revista Española de Micropaleontología. 40 (1–2): 77–96. ISSN 0556-655X.

Bibliography

• Figari, Eduardo G.; Roberto A. Scasso; Rubén N. Cúneo, and Ignacio Escapa. 2015. Estratigrafía y evolución geológica de la Cuenca de Cañadón Asfalto, Provincia del Chubut, Argentina. Latin American Journal of Sedimentology and Basin Analysis 22. 135–169. Accessed 2018-09-10.
• Weishampel, David B.; Peter Dodson, and Halszka Osmólska (eds.). 2004. The Dinosauria, 2nd edition, 1–880. Berkeley: University of California Press. Accessed 2019-02-21.ISBN 0-520-24209-2