[D] Lagosuchus lilloensis
Describer
Romer, 1972 vide Sereno & Arcucci, 1994
Time
Triassic
Classification
Lagosuchia Lagosuchidae Not considered dinosaur
Fossilsite
Argentina
Fall Under
Marasuchus lilloensis
Length
0.30 meter
Info
Marasuchus lilloensis (Sereno& Arcucci, 1994) >> Lagosuchus lilloensis (Romer, 1972 vide Sereno & Arcucci, 1994)
Lagosuchus lilloensis, is represented by more complete and better preserved remains then Lagosuchus talampayensis.The widely known reconstruction of \\\'Lagosuchus\\\' is based upon the \\\'Lagosuchus\\\' lilloensis material. Bonaparte later considered L. lilloensis as a junior synonym to Lagosuchus talampayensis. However, Paul Sereno restudied the specimens and came to the conclusion that the holotype of \\\'\\\'Lagosuchus\\\' talampayensis possesses no autapomorphies and might even be a chimaera. The \\\'Lagosuchus\\\' lilloensis material does have definite autapomorphies which are not preserved in the holotype of Lagosuchus talampayensis. Sereno regarded the genus Lagosuchus and the species talampayensis as nomina dubia and transferred the species lilloensis to the new genus Marasuchus (Mara is a Patagonian saltatory rodent, Sereno wanted to retain the original spirit of Romer\\\'s name).
Many people have split the genus into two, leaving only the type species in Lagosuchus. The better known, that is better preserved, species was moved to Marasuchus. Sereno and Arcucci, 1994 also restudied Lagosuchus and concluded that the type specimen was too poorly preserved to refer material to it whit confidence; moreover, the proportions of the forelimb and hindlimb were different from those in other, better preserved specimens referred to the species. They decided to restrict L. talampayensis to the relatively poorly preserved type specimen and erected a new genus, Marasuchus lilloensis for reception of the referred material as well as the type material of Lagosuchus lilloensis Romer, which they concluded was not specifically different.
In all particulars except the proportions of the forelimb, however, the type material of Lagosuchus talampayensis agrees with other Lagosuchus material, and wheter or not the association of this forelimb with the type specimen is firmly established, Lagosuchus and Marasuchus are in other respects phylogenetically indistinguishable. The acetabulum was reported by Bonaparte (1975) as partly open, but this may be an artifact of preservation.
The foot is also more dinosaurian than that of Lageropeton because the asymmetry of the digits is not as pronounced, and the third toe is the longest. Additionally the vertebral column is well regionalized, with directe cervical, anterior dorsal, and posterior dorsal vertebrae, as contrasted with thos of Pseudosuchia (Bonaparte 1975,; Sereno and Arcucci, 1994)
These features suggest a bidepal animal with more or less horizontal back and arched neck, running rapidly on hindlimbs that had elongated tibiae and metatarsals for improved cursorial abilities.
Romer, 1972 vide Sereno & Arcucci, 1994
Time
Triassic
Classification
Lagosuchia Lagosuchidae Not considered dinosaur
Fossilsite
Argentina
Fall Under
Marasuchus lilloensis
Length
0.30 meter
Info
Marasuchus lilloensis (Sereno& Arcucci, 1994) >> Lagosuchus lilloensis (Romer, 1972 vide Sereno & Arcucci, 1994)
Lagosuchus lilloensis, is represented by more complete and better preserved remains then Lagosuchus talampayensis.The widely known reconstruction of \\\'Lagosuchus\\\' is based upon the \\\'Lagosuchus\\\' lilloensis material. Bonaparte later considered L. lilloensis as a junior synonym to Lagosuchus talampayensis. However, Paul Sereno restudied the specimens and came to the conclusion that the holotype of \\\'\\\'Lagosuchus\\\' talampayensis possesses no autapomorphies and might even be a chimaera. The \\\'Lagosuchus\\\' lilloensis material does have definite autapomorphies which are not preserved in the holotype of Lagosuchus talampayensis. Sereno regarded the genus Lagosuchus and the species talampayensis as nomina dubia and transferred the species lilloensis to the new genus Marasuchus (Mara is a Patagonian saltatory rodent, Sereno wanted to retain the original spirit of Romer\\\'s name).
Many people have split the genus into two, leaving only the type species in Lagosuchus. The better known, that is better preserved, species was moved to Marasuchus. Sereno and Arcucci, 1994 also restudied Lagosuchus and concluded that the type specimen was too poorly preserved to refer material to it whit confidence; moreover, the proportions of the forelimb and hindlimb were different from those in other, better preserved specimens referred to the species. They decided to restrict L. talampayensis to the relatively poorly preserved type specimen and erected a new genus, Marasuchus lilloensis for reception of the referred material as well as the type material of Lagosuchus lilloensis Romer, which they concluded was not specifically different.
In all particulars except the proportions of the forelimb, however, the type material of Lagosuchus talampayensis agrees with other Lagosuchus material, and wheter or not the association of this forelimb with the type specimen is firmly established, Lagosuchus and Marasuchus are in other respects phylogenetically indistinguishable. The acetabulum was reported by Bonaparte (1975) as partly open, but this may be an artifact of preservation.
The foot is also more dinosaurian than that of Lageropeton because the asymmetry of the digits is not as pronounced, and the third toe is the longest. Additionally the vertebral column is well regionalized, with directe cervical, anterior dorsal, and posterior dorsal vertebrae, as contrasted with thos of Pseudosuchia (Bonaparte 1975,; Sereno and Arcucci, 1994)
These features suggest a bidepal animal with more or less horizontal back and arched neck, running rapidly on hindlimbs that had elongated tibiae and metatarsals for improved cursorial abilities.