Amargasuchus

Amargasuchus
Temporal occurrence
	Lower Cretaceous (Lower Barremium )
	130.7 to 129.4 million years
Locations
	Neuquén , Argentina ( La Amarga Formation );
Systematics
	Archosauromorpha
	Archosauria
	Crurotarsi
	Crocodylomorpha
	Mesoeucrocodylia
	Amargasuchus
Scientific name
	Amargasuchus
	Chiappe , 1988
Art
	Amargasuchus minor;

Amargasuchus is an extinct genus from the Mesoeucrocodylia group , which originated in the Lower Cretaceous Argentina . The Mesoeucrocodylia include today's crocodiles and various crocodile-like groups; however, the systematic position of Amargasuchus within the Mesoeucrocodylia is unclear. So far, only a single fragmentary upper jaw is known that comes from the La Amarga Formation andcan be datedto the Lower Barremium . The only species is Amargasuchus minor .

features

Amargasuchus was a small crocodile. The preserved section of the upper jaw measures a length of 4.16 cm, the entire skull would have shown a length of about 9 to 10 cm. The muzzle was narrow and moderate in height, the underside of the upper jaw was straight. Amargasuchus had an antorbital window , an additional skull window located in front of the eye , which is typical for representatives of the archosaurs , but is missing in today's crocodiles. The preserved section of the upper jaw has 13 tooth sockets (alveoli), but the teeth themselves are not preserved. From the shape of the tooth sockets, however, it can be concluded that the teeth were laterally flattened. The teeth corresponded in size, greatly enlarged ( hypertrophic ) teeth were missing.

Systematics

In his first description , Luis Chiappe (1988) assigned Amargasuchus to the Trematochampsidae , a group within the Mesoeucrocodylia to which the genera Trematochampsa and Hamadasuchus are assigned. Diego Pol and Zulma Gasparini (2007) note, however, that the Trematochampsidae are a problematic and insufficiently defined group, and that the current evidence would not be sufficient to reliably assign Amargasuchus to this group. Instead, these researchers classify Amargasuchus as a representative of the Mesoeucrocodylia (Mesoeucrocodylia incertae sedis) that cannot be classified further and thus forego a more precise classification of this genus.

Find history

The find was discovered in 1984 by an expedition led by José Bonaparte . It was found together with the skeleton of the sauropod dinosaur Amargasaurus . The site is located about 70 km south of the city of Zapala in the Argentine province of Neuquén . The find ( holotype , copy number MACN-N-12) is kept in the collection of the Museo Argentino de Ciencias Naturales Bernardino Rivadavia in Buenos Aires .

The name Amargasuchus refers to the La Amarga formation, from which the find comes. The second part of the species name, minor , indicates the small size of this crocodile.

supporting documents

↑ ^a ^b ^c ^d Diego Pol, Zulma Gasparini: Crocodyliformes. In: Zulma Gasparini, Leonardo Salgado , Rodolfo A. Coria : Patagonian Mesozoic Reptiles. Indiana University Press, Bloomington et al. IN 2007, ISBN 978-0-253-34857-9 , pp. 122-124.
↑ ^a ^b ^c ^d ^e Luis M. Chiappe : A new trematochampsid crocodile from the Early Cretaceous of north-western Patagonia, Argentina and its palaeobiogeographical and phylogenetic implications. In: Cretaceous Research. Vol. 9, No. 4, 1988, ISSN 0195-6671 , pp. 379-389, doi : 10.1016 / 0195-6671 (88) 90009-2

[pol_07-1] Diego Pol, Zulma Gasparini: Crocodyliformes. In: Zulma Gasparini, Leonardo Salgado , Rodolfo A. Coria : Patagonian Mesozoic Reptiles. Indiana University Press, Bloomington et al. IN 2007, ISBN 978-0-253-34857-9 , pp. 122-124.

[chiappe_88-2] Luis M. Chiappe : A new trematochampsid crocodile from the Early Cretaceous of north-western Patagonia, Argentina and its palaeobiogeographical and phylogenetic implications. In: Cretaceous Research. Vol. 9, No. 4, 1988, ISSN 0195-6671 , pp. 379-389, doi : 10.1016 / 0195-6671 (88) 90009-2