:La Amarga Formation

{{Infobox rockunit

| name = La Amarga Formation

| image =

| caption =

| type = Geological formation

| period = Aptian

| age = Barremian-Early Aptian
~{{fossil range|130|120}}

| prilithology = Sandstone

| otherlithology = Mudstone

| namedfor = La Amarga Arroyo

| namedby = Musacchio

| year_ts = 1970

| region = Río Negro, Mendoza & Neuquén Provinces

| country = Argentina

| coordinates = {{coord|39.6|S|70.2|W|display=inline,title}}

| paleocoordinates = {{coord|39.6|S|35.2|W|display=inline}}

| unitof = Rayoso Group

| subunits = Puesto Antigual, Bañados de Caichigüe & Piedra Parada Members

| underlies = Lohan Cura Formation

| overlies = Agrio Formation

| thickness = {{convert|160|m|ft|abbr=on}}

| extent = Neuquén Basin

| area =

| map = {{Location map+ | Argentina

| relief = 1

| width = 250

| float = center

| places =

{{Location map~ | Argentina

| lat_deg = -39.6

| lon_deg = -70.2

| mark = Green pog.svg

| marksize = 12

}}

| map_caption =

}}

The La Amarga Formation is a geologic formation with outcrops in the Argentine provinces of Río Negro, Neuquén, and Mendoza. It is the oldest Cretaceous terrestrial formation in the Neuquén Basin.

The type locality is La Amarga Arroyo and China Muerta Hill.Musacchio, 1970 The La Amarga Formation unconformably overlies the marine Agrio Formation of the Mendoza Group. It is in turn overlain by the Lohan Cura Formation, separated by another unconformity.

Composition

There are three members within the La Amarga Formation.

The oldest is the Puesto Antigual Member, which is approximately {{convert|28.9|m|ft}} thick and consists mainly of sandstone deposited in the channels of a braided river system. Paleosols, or soil deposits, are well-developed.
The Bañados de Caichigüe Member is the next highest, approximately {{convert|20.9|m|ft}} thick. Alternating limestones, shales, and siltstones make up this member, indicating a lacustrine (lake) environment.
Youngest and thickest is the Piedra Parada Member, approximately {{convert|109.4|m|ft}} thick in some sections. This member consists of alternating sandstones and siltstones from an ancient alluvial plain, with some swamp and paleosol deposits.

Fossil content

Most of the tetrapod fossils found in the La Amarga come from the Puesto Antigual Member.

= Dinosaurs =

colspan="6" align="center" \| Dinosaurs
class="wikitable" style="text-align:center"
Genus ! Species ! Location ! Stratigraphic position ! Material ! Images
AmargasaurusWeishampel et al., 2004, "Dinosaur distribution (Early Cretaceous, South America).", pp. 563–570 \| A. cazaui \| Neuquén \| Puesto Antigual \| "Braincase and associated postcranial skeleton.""Table 13.1," in Weishampel et al., 2004, p. 264 \| File:Amargasaurus NT small.jpg
Amargatitanis \| A. macni \| Neuquén \| Puesto Antigual \| "Two caudal vertebrae, an incomplete right ischium, a right femur, an incomplete right tibia, an incomplete right fibula, a right astragalus, and an incomplete right metatarsal I." \| File:Amargatitanis LM.png
Ligabueino \| L. andesi \| Neuquén \| Puesto Antigual \| "A cervical neural arch, a mid to posterior dorsal neural arch, a posterior dorsal centrum, the left femur, left ilium, articulated pubic shafts, and two pedal phalanges."Carrano et al., 2011 \|
Zapalasaurus \| Z. bonapartei \| Neuquén \| Piedra Parada \| \|
Stegosauria indet. \| Indeterminate \| Neuquén \| Puesto Antigual \| "Supraorbital, cervical and caudal vertebrae, dermal armor".Galton & Carpenter, 2016Pereda Suberbiola et al., 2012 \|

= Other tetrapods =

class="wikitable" style="text-align:center"

colspan="6" align="center" | Other tetrapods

Genus

! Species

! Location

! Stratigraphic position

! Material

! Images

Amargasuchus

A. minor

Neuquén

Puesto Antigual

A trematochampsid crocodylomorph, found in association with the holotype of Amargasaurus

Pterosauria indet.Montanelli, 1987

Indeterminate

Neuquén

An isolated femur

Vincelestes

V. neuquenianus

Neuquén

Puesto Antigual

A cladotherian mammal

File:Artistic_reconstruction_of_Vincelestes.PNG

References

= Bibliography =

{{cite journal |last1=Galton |first1=Peter M. |last2=Carpenter |first2=Kenneth |year=2016 |title=The plated dinosaur Stegosaurus longispinus Gilmore, 1914 (Dinosauria: Ornithischia; Upper Jurassic, western USA), type species of Alcovasaurus n. gen. |journal=Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen |volume=279 |issue=2 |pages=185–208|doi=10.1127/njgpa/2016/0551 }}
{{cite journal |last1=Pereda Suberbiola |first1=Xabier |last2=Galton |first2=Peter M. |last3=Mallison |first3=Heinrich |last4=Novas |first4=Fernando |year=2012 |title=A plated dinosaur (Ornithischia, Stegosauria) from the Early Cretaceous of Argentina, South America: an evaluation |journal=Alcheringa: An Australasian Journal of Palaeontology |volume=37 |issue=1 |pages=1–14}} {{doi|10.1080/03115518.2012.702531}}
{{cite journal |last1=Carrano |first1=M.T. |last2=Loewen |first2=M.A. |last3=Sertic |first3=J.J.W. |year=2011 |title=New Materials of Masiakasaurus knopfleri Sampson, Carrano, and Forster, 2001, and Implications for the Morphology of the Noasauridae (Theropoda: Ceratosauria) |journal=Smithsonian Contributions to Paleobiology |volume=95 |issue=95 |pages=1–53|doi=10.5479/si.00810266.95.1 |url=https://www.biodiversitylibrary.org/bibliography/159033 }}
{{cite book |editor-last1=Weishampel |editor-first1=David B. |editor-last2=Dodson |editor-first2=Peter |editor-last3=Osmólska |editor-first3=Halszka |year=2004 |title=The Dinosauria, 2nd edition |url=https://books.google.com/books?id=vtZFDb_iw40C |publisher=Berkeley: University of California Press |pages=1–880 |isbn=978-0-520-94143-4 |accessdate=2019-02-21}} {{ISBN|0-520-24209-2}}
{{cite journal |last=Montanelli |first=S. B |year=1987 |title=Presencia de Pterosauria (Reptilia) en la Formación La Amarga (Hauteriviano-Barremiano), Neuquén, Argentina |journal=Ameghiniana |volume=24 |pages=109–113}}
{{cite journal |last=Musacchio |first=E |year=1970 |title=Ostrácodos de la superfamilias Cytheraceae y Darwinulaceae de la Formación La Amarga (Cretácico inferior), provincia del Neuquén, Argentina |journal=Ameghiniana |volume=7 |pages=301–318}}

:La Amarga Formation

Composition

Fossil content

= Dinosaurs =

= Other tetrapods =

See also

References

= Bibliography =

Further reading