PREVOSTI Francisco Juan
congresos y reuniones científicas
The Badlands from Mendoza and the Huayquerian Age: insights into the Late Miocene.
Congreso; IV International Paleontological Congress; 2014
The badlands exposed in central-northern Mendoza, Argentina, have been the subject ofpaleontological studies in the first half of the 20th century. The area is a large faulted anticline withthe Huayquerías Formation cropping out in the east. This formation is estimated to date from lessthan 10.5/9.5 Ma (dating from the lower Tobas Angostura Formation) to 5.8 Ma (dating from theupper levels of the Huayquerías Formation). The Huayquerian Age (late Miocene) was defined onthe basis of a small mammalian association from the Huayquerías Formation and currently includes:Megatheriops rectidens (Megatheriidae), Proscelidodon gracillimus (Mylodontidae), Hemihegetotheriumachataleptum (Hegetotheriinae), ?Proterotherium? sp. (Proterotheriidae), Huayqueriana cristata(Macraucheniidae), Cyonasua pascuali (Procyonidae), and Lagostomus pretrichodactyla (Chinchillidae).Consequently, the Huayquerian Age is currently characterized by other associations from SouthAmerica that are considered to be equivalent in time. This grouping, along with inclusion oftaxa with controversial geographical and stratigraphical location renders the definition of theHuayquerian Age imprecise. New field work has been conducted in the Huayquerías Formationwith the aim of characterizing this age with the faunal content from the type locality. The newfindings (housed in IANIGLA-PV) include Macrochorobates? sp., Chasicotatus cf. Ch. ameghinoi, andChorobates sp. (Dasypodidae), Paedotherium sp. and Tremacyllus sp. (Pachyrukhinae), a probable newMacraucheniidae (Litopterna), cf. Cyonasua larger than C. pascuali (Procyonidae), Pseudoplataeomysaff. P. formosus, Pithanotomys? and Palaeoctodon sp. (Octodontidae), aff. Palaeocavia (Caviidae)and Lagostomus pretrichodactyla (Chinchillidae). Also recovered were vertebrae of Boidae indet.(Serpentes), a maxilla referred to cf. Ceratophrys sp. (Anura), large tridactyl footprints referredto Macrauchenichnus rector, an ichnogenus that could be used to represent litopterns, and smalltridactyl footprints produced by rodent-like mammals, possibly small notoungulates. Theseinclude the first footprints found in the Huayquerías Formation and 13 new taxa, elevating thetaxonomic list from seven to 20 taxa. This association is currently accepted to be largely congruentwith other late Miocene faunas referred to the Huayquerian Age. Uncertainties exist with the rodentPseudoplataeomys aff. P. formosus. Previously, only the holotype of P. formosus was known, collectedfrom Monte Hermoso (Buenos Aires, type locality of the Montehermosan Age, lower Pliocene),lacking precise stratigraphic data. Although this recent work has expanded the taxonomic list,the association remains small compared to other assemblages. Further work may append manymore taxa to the list with the potential to improve the definition of the Huayquerian Age and itscalibration in the biostratigraphic chart of the late Neogene.