Marasuchus

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search

Marasuchus
Temporal range: Late Triassic, 235–234 Ma
Marasuchus.JPG
Restored skeleton
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauriformes
Genus: Marasuchus
Sereno & Arcucci, 1994
Species: M. lilloensis
Binomial name
Marasuchus lilloensis
(Romer, 1972 [originally Lagosuchus])
Synonyms
  • Lagosuchus lilloensis (Romer, 1972)

Marasuchus (meaning "Mara crocodile") is a genus of basal dinosauriform archosaur which lived during the late Triassic in what is now La Rioja Province, Argentina.

Description

Life restoration of M. lilloensis with featherlike filaments

Marasuchus was lightly built and small, it had a length of 30 to 40 cm (1.0 to 1.3 ft), height of 10 cm (0.3 ft) and estimated weight of 2 to 5 kilograms (4.4 to 11.0 lb).[1][2] It was bipedal, walking with an upright (parasagittal) gait, like that of modern mammals and birds.[2]

One of the diagnostic features of dinosaurs, a hole in the hip socket (acetabulum) of the pelvis for the femur (thighbone), is absent in Marasuchus; however, it possessed characteristics, such as an elongate pubis and the presence of an anterior trochanter on the femur, similar to those found in dinosaurs. The presence of these characteristics in Marasuchus shows that some of the features limited to dinosaurs and their close relatives had begun to evolve in the Middle Triassic prior to the formal origin of dinosaurs in the Late Triassic.[2]

Classification

Life restoration (without feather-like filaments) comparesd to human legs.

Until 2003 Marasuchus was thought to be one of the closest relatives of the dinosaurs. At present it has been supplanted by other dinosauromorphs such as Silesaurus. Nonetheless, Marasuchus remains an important animal for understanding the origin and evolution of dinosaur characteristics.[2] The following is a cladogram of basal Dinosauriformes according to Nesbitt (2011), and Dinosauria according to Baron et al. (2017):

 Dinosauromorpha 

Lagerpetonidae

 Dinosauriformes 

Marasuchus Marasuchus.jpg

SilesauridaeSilesaurus opolensis flipped.jpg

 Dinosauria 
Saurischia

HerrerasauridaeHerrerasaurus ischigualastensis Illustration.jpg

SauropodomorphaBarapasaurus DB.jpg

Ornithoscelida

OrnithischiaTriceratops liveDB.jpg

TheropodaMeyers grosses Konversations-Lexikon - ein Nachschlagewerk des allgemeinen Wissens (1908) (Antwerpener Breiftaube).jpg

Discovery and history

Alfred Romer first discovered fossils of the species in the 1960s in the Chañares Formation of the Ischigulasto-Villa Unión Basin in northwestern Argentina, all parts of the reptile’s skeletal anatomy are known from fossils except for the skull and lower jaw.[1][2] The formation was dated as being 235 to 234 million years old.[3]

Lagosuchus

Two species have been named, L. talampayensis and L. lilloensis. The genus (Lagosuchus) and type species (L. talampayensis) are regarded as nomina dubia. The species Marasuchus lilloensis was originally described as a second species of Lagosuchus, L. lilloensis. However, in a restudy of Lagosuchus by Sereno and Arcucci (1994), the authors concluded that the original (type) specimen was too poorly preserved to allow any further specimens to be assigned to the genus. They also noted that the L. lilloensis specimen had limb proportions different from the type species. On this basis, they assigned L. lilloensis to a new genus, Marasuchus.[4]

References

  1. ^ a b Benton, Michael; Brusatte, Steve (25 October 2012). Dinosaurs. UK: Hachette. p. 24. ISBN 1780875738. Retrieved 31 March 2016.
  2. ^ a b c d e Rafferty, John P, ed. (1 April 2010). The Mesozoic Era: Age of Dinosaurs. Britannica Educational Publishing. p. 126. ISBN 1615301933. Retrieved 31 March 2016.
  3. ^ Claudia A. Marsicano; Randall B. Irmis; Adriana C. Mancuso; Roland Mundil; Farid Chemale (2016). "The precise temporal calibration of dinosaur origins". Proceedings of the National Academy of Sciences of the United States of America. 113 (3): 509–513. doi:10.1073/pnas.1512541112. PMC 4725541. PMID 26644579.
  4. ^ Sereno, Paul C. and Arcucci, Andrea B. (1994). "Dinosaurian precursors from the Middle Triassic of Argentina: Marasuchus lilloensis gen. nov." Journal of Vertebrate Paleontology 14: 53-73 Chicago, IL Abstract
Retrieved from "https://en.wikipedia.org/w/index.php?title=Marasuchus&oldid=861736804"
This content was retrieved from Wikipedia : http://en.wikipedia.org/wiki/Marasuchus
This page is based on the copyrighted Wikipedia article "Marasuchus"; it is used under the Creative Commons Attribution-ShareAlike 3.0 Unported License (CC-BY-SA). You may redistribute it, verbatim or modified, providing that you comply with the terms of the CC-BY-SA