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Motion range of the manus of Plateosaurus engelhardti von Meyer, 1837

Stefan Reiss and Heinrich Mallison

Plain Language Abstract

The hands of a biped and a quadruped are subjected to different evolutionary pressures, because the latter needs it to be able to support its weight during locomotion. We used digital files to analyse the motion range and grasping capabilities of the hand of Plateosaurus, to determine if the hand was suitable for carrying weight, and thus find out if Plateosaurus was a quadruped.

The results indicate that Plateosaurus was not able to use its hands during locomotion, in agreement with previous studies.

Resumen en Español

Rango de movimiento de la mano de Plateosaurus engelhardti von Meyer, 1837
El modo de locomoción del sauropodomorfo basal Plateosaurus engelhardti, conocido por numerosos hallazgos del Triásico terminal de Europa central, ha sido ampliamente debatido. Algunos resultados de las investigaciones iniciales y recientes indican que la extremidad anterior no pudo jugar un papel en la locomoción cuadrúpeda. Otros autores sugirieron una condición cuadrúpeda facultativa o incluso permanente. Esto requeriría adaptaciones a las altas fuerzas causadas por la locomoción, tanto en el rango de movimiento como en la estabilidad de los dígitos manuales. Un análisis de las capacidades de hiperextensión de la mano puede, por tanto, determinar si está adaptada para la locomoción. Este estudio examina las capacidades de la mano de P. engelhardti utilizando la modelización 3D digital. Se simularon los rangos de movimiento de los dedos con un programa (CAE) de ingeniería asistida por computadora, y la capacidad de hiperextensión de toda la mano en su conjunto se puso a prueba.

Descubrimos que la mano de Plateosaurus no era capaz de soportar al animal durante una locomoción cuadrúpeda, sino que más bien pudo haber sido un órgano de agarre especializado. Por lo tanto, P. engelhardti debió ser un bípedo obligado.

Palabras clave: Plateosaurus; rango de movimiento; paleontología virtual

Traducción: Enrique Peñalver

Résumé en Français

La gamme de mouvement de la main de Plateosaurus engelhardti von Meyer, 1837

Le mode de locomotion du sauropodomorphe basal Plateosaurus engelhardti, connu grâce à de nombreuses découvertes de la fin du Trias de l'Europe centrale, a été largement débattue. Certains résultats de recherche antérieurs et récents indiquent que la patte antérieure ne pouvait pas jouer un rôle dans la locomotion quadrupède. D'autres auteurs ont suggéré une locomotion quadrupède facultative ou même permanente. Cela nécessiterait certaines adaptations dans la gamme des mouvements et une stabilité des doigts de la main lorsque des forces élevées sont appliquées pendant la locomotion. Une analyse des capacités d'hyper-extension de la main peut donc déterminer si la main est adaptée à la locomotion. Cette étude examine les capacités de la main de P. engelhardti, utilisant la modélisation numérique 3D. Les gammes de mouvement des doigts ont été simulées dans un programme d'ingénierie assistée par ordinateur (CAE), et la capacité d'hyper-extension de la totalité de la main a été testée.

Nous constatons que la main de Plateosaurus n'était pas en mesure de soutenir l'animal lors de la locomotion quadrupède, mais peut-être plutôt avons été un organe de préhension spécialisé. Par conséquent, P. engelhardti doit avoir été un bipède obligatoire.

Mots-clés: Plateosaurus; gamme de mouvement; paléontologie virtuelle

Translator: Kenny J. Travouillon

Deutsche Zusammenfassung

Beweglichkeit der Hand von Plateosaurus engelhardti von Meyer, 1837

Die Art der Fortbewegung des basalen Sauropodomoprhen Plateosaurus engelhardti, von dem viele Fund aus der oberen Trias Mitteleuropas bekannt sind, ist ausführlich diskutiert worden. Eine frühe und neuere Studienergebnisse deuten darauf hin, dass das Vorderbein keine Rolle bei der Fortbewegung spielen konnte. Andere Autoren schlagen dagegen fakultative oder sogar permanente Vierbeinigkeit vor. Diese würde erfordern, dass von der Fortbewegung ausgelöste Anpassungen in den Bewegungsradien und der Stabilität der Finger bestehen. Eine Analyse der Fähigkeit zur Fingerüberstreckung in der Hand kann daher feststellen, ob die Hand für die Fortbewegung geeignet ist. Diese Studie untersucht die Fähigkeiten der Hand von P. engelhardti mittels digitaler 3D-Modellierung. The Bewegungsradien der Finger wurden in einem Computer Aided Engineering (CAE) Programm simuliert, und die Überstreckbarkeit der gesamten Hand getestet.

Es zeigt sich, dass die Hand von Plateosaurus nicht in der Lage war, das Tier bei quadrupeder Fortbewegung zu stützen, sondern eher in Greiforgan war. Daher muss Plateosaurus obligat biped gewesen sein.

 Schlüsselwörter: Plateosaurus; Beweglichkeit; virtuelle Paläontologie

Translator: authors

Arabic

428 arab

Translator: Ashraf M.T. Elewa

 

 

Stefan Reiss
Steinmann-Institut für Geologie
Mineralogie und Paläontologie
Rheinische Friedrich-Wilhelms-Universität Bonn
Germany
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mallisonHeinrich Mallison
Museum für Naturkunde - Leibniz-Institut für Evolutions - und Biodiversitätsforschung
Berlin, Germany
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Heinrich Mallison studied Geology/ Paleontology at Tübingen University in southern Germany. After a brief stint in palaeobotany, working on fossil pine cones, he received a doctorate (Dr. rer. nat.) for his work on developing computer aided design and computer aided engineering modeling methods for vertebrate paleontology in 2007. This project was part of the Research Unit FOR 533 'Biology of sauropod gigantism' of the German Science Foundation (GSF) and dealt mostly with the locomotion of the 'prosauropod' Plateosaurus.

Heinrich currently continues his work on digitizing and NASTRAN-based kinetic/dynamic modeling techniques as head (and sole member) of a project at the Museum für Naturkunde in Berlin (MFN), again part of GSF FOR 533, modeling sauropod locomotion and related aspects.

Other current research activities involve a revision of Plateosaurus material in the MFN, cranial kinesis in large theropods, and stegosaur defense mechanisms.

If research and family allow, Heinrich prefers to spend his summer holidays digging for dinosaurs.

 

 

TABLE 1. Maximum flexion angles of phalanges in relation to the long axis of the metacarpus.

 

Bone

angle [deg]
max. flexion

angle [deg]
max. extension

mPh-I-1

59.8

-27.8

mPh-I-2

151

-49.4

mPh-II-1

49.6

-29.6

mPh-II-2

108

-54.7

mPh-II-3

189

-84.4

mPh-III-1

50

-40

mPh-III-2

99.6

-59.7

mPh-III-3

170

-74.7

mPh-III-4

237

-104

mPh-IV-1

77.8

-12.5

mPh-IV-2

128

-32.6

mPh-V-1

90

-29.6

mPh-V-2

172

-73

 

FIGURE 1. Plateosaurus engelhardti specimen "GPIT Skelett 2" in the Paläontologische Lehr- und Schausammlung, Fachbereich Geowissenschaften of the Eberhard Karls Universität Tübingen (PLSST). Left: Lateral view of the skeletal mount erected under the direction of Friedrich von Huene. Right: Close up view of the lower left forelimb and hand.

figure1

FIGURE 2. Articulated, CT-scan based digital scans of the left hand of Plateosaurus engelhardti specimen "GPIT Skelett 2" in the PLSST in dorsal view. Compare to Figure 1.

figure2

FIGURE 3. Digital files of metacarpal I and the phalanges of digit I of the left hand of Plateosaurus engelhardti specimen "GPIT Skelett 2" in dorsal (left) and lateral (right) views, showing straight (ONP) position, and slight and full extension and flexion. Figures 3 through 8 to same scale.

figure3

FIGURE 4. Digital files of metacarpal II and the phalanges of digit II of the left hand of Plateosaurus engelhardti specimen "GPIT Skelett 2" in dorsal view, showing straight (ONP) position, and slight and full extension and flexion. Figures 3 through 8 to same scale.

figure4

FIGURE 5. Digital files of metacarpal II and the phalanges of digit II of the left hand of Plateosaurus engelhardti specimen "GPIT Skelett 2" in lateral view, showing straight (ONP) position, and slight and full extension and flexion. Figures 3 through 8 to same scale.

figure5

FIGURE 6. Digital files of metacarpal III and the phalanges of digit III of the left hand of Plateosaurus engelhardti specimen "GPIT Skelett 2" in dorsal view, showing straight (ONP) position, and slight and full extension and flexion. Figures 3 through 8 to same scale.

figure6 

FIGURE 7. Digital files of metacarpal III and the phalanges of digit III of the left hand of Plateosaurus engelhardti specimen "GPIT Skelett 2" in lateral view, showing straight (ONP) position, and slight and full extension and flexion. Figures 3 through 8 to same scale.

figure7

FIGURE 8. 1. Digital files of metacarpal IV and the phalanges of digit IV of the left hand of Plateosaurus engelhardti specimen "GPIT Skelett 2" in dorsal view showing straight (ONP) position, and slight and full extension and flexion. 2.-4. Digital files of metacarpal V and the phalanges of digit V of the left hand of Plateosaurus engelhardti specimen "GPIT Skelett 2" showing straight (ONP) position, and slight and full flexion in 2. lateral (in relation to the entire manus) and 3. lateral (in relation to digit V) views, and 4. dorsal view showing straight (ONP) position, slight and full extension. Figures 3 through 8 to same scale.

figure8