FORELIMB POSTURE IN CHILESAURUS DIEGOSUAREZI (DINOSAURIA, THEROPODA) AND ITS BEHAVIORAL AND PHYLOGENETIC IMPLICATIONS

Authors

  • Nicolás Roberto Chimento Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"
  • Federico Lisandro Agnolin Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"
  • Fernando Emilio Novas Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"
  • Martin Daniel Ezcurra Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"
  • Leonardo Salgado CONICET Instituto de Investigación en Paleobiología y Geología, Universidad Nacional de Río Negro
  • Marcelo Isasi Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"
  • Manuel Suarez Carrera Geología, Facultad de Ingeniería, Universidad Andrés Bello
  • Rita De la Cruz Servicio Nacional de Geología y Minería
  • David Rubilar-Rogers Área Paleontología, Museo Nacional de Historia Natural
  • Alexander Vargas Laboratorio de Ontogenia y Filogenia, Departamento de Biología, Facultad de Ciencias, Universidad de Chile

Keywords:

Forelimb resting posture, soft tissue, flexion, flight evolution

Abstract

Many dinosaur skeletons show evidence of behavior, including feeding, predation, nesting, and parental care. The resting posture of the forelimbs has been studied in some theropod species, in relation to the acquisition of flight in advanced maniraptoran theropods. Chilesaurus diegosuarezi is a bizarre tetanuran recently described from the Toqui Formation (latest Tithonian) of southern Chile that is represented by multiple well-preserved and articulated specimens. The aim of the present work is to analyze the forelimb posture of four articulated specimens of Chilesaurus: SNGM-1935 (holotype), SNGM-1936, SNGM-1937, SNGM-1938; focusing on its anatomical description, and phylogenetic and behavioral implications. All the preserved specimens of Chilesaurus show strongly ventrally flexed arms with the hands oriented backwards, an arraignment that closely resembles those in dinosaur specimens previously described as preserving resting posture, such as Mei long, Sinornithoides youngi, and Albinykus baatar. As a result, it seems that individuals of Chilesaurus have been in passive activity (e.g. feeding, resting) when they were buried quickly, allowing their fossilization in life position and preserving the forelimb resting posture. The arraignment of the forelimb bones in Chilesaurus could show the first evidences of the structures linked to the muscles that flex the forearms, features related with the acquisition of flying control in advanced maniraptorans.

Author Biographies

Nicolás Roberto Chimento, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"

Laboratorio de Anatomia Comparada y Evolucion de los Vertebrados

Federico Lisandro Agnolin, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"

Laboratorio de Anatomia Comparada y Evolucion de los Vertebrados

Fernando Emilio Novas, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"

Laboratorio de Anatomia Comparada y Evolucion de los Vertebrados

Martin Daniel Ezcurra, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"

Sección Paleontología de Vertebrados

Marcelo Isasi, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"

Laboratorio de Anatomia Comparada y Evolucion de los Vertebrados

Published

2017-11-14

How to Cite

Chimento, N. R., Agnolin, F. L., Novas, F. E., Ezcurra, M. D., Salgado, L., Isasi, M., Suarez, M., De la Cruz, R., Rubilar-Rogers, D., & Vargas, A. (2017). FORELIMB POSTURE IN CHILESAURUS DIEGOSUAREZI (DINOSAURIA, THEROPODA) AND ITS BEHAVIORAL AND PHYLOGENETIC IMPLICATIONS. Ameghiniana, 54(5), 567–575. Retrieved from https://www.ameghiniana.org.ar/index.php/ameghiniana/article/view/3088

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