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Hungarosaurus partial skull from the Upper Cretaceous (Santonian) of Iharkút (western Hungary). Click on image to run animation.

 

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Partial skull and endocranial cast of the ankylosaurian dinosaur Hungarosaurus from the Late Cretaceous of Hungary: implications for locomotion

Attila Ősi, Xabier Pereda Suberbiola, and Tamás Földes

Plain Language Abstract

Ankylosaur remains from the Upper Cretaceous of Europe are very rare, thus every new piece of ankylosaur bone is important for a better understanding of the paleobiology and relationships of these armored dinosaurs.

A partial skull of ankylosaur discovered from Upper Cretaceous beds in Iharkút, Hungary and the silicone rubber mould taken from it are described in this study. The morphology of the bones clearly distinguish it from other ankylosaurs, thus it is assigned here to Hungarosaurus already known from the locality. Whereas the endocranial cast reflects a brain generally similar to those of other ankylosaurs, the dorsally expanded small brain region is quite unusual within the group suggesting a more sophisticated cerebral coordination of posture and movement and perhaps a more cursorial locomotary habit than predicted for other ankylosaurs.

Resumen en Español

Cráneo parcial y molde endocraneal del dinosaurio anquilosaurio Hungarosaurus del Cretácico superior de Hungría: implicaciones locomotoras

Se describe un cráneo parcial de anquilosaurio y su correspondiente molde endocraneal del Cretácico superior (Santoniense) del yacimiento de Iharkút (Formación Csehbánya). La morfología del exoccipital, la presencia de un "cuello" alargado en el basioccipital, la forma del cóndilo occipital y la diferente flexión de la médula en relación con la parte anterior del cerebro permiten diferenciarlo claramente del basicráneo de Struthiosaurus, por lo que se asigna a Hungarosaurus sp. Mientras que el molde endocraneal muestra que el cerebro era similar al de otros anquilosaurios, la presencia de un cerebelo dorsalmente hipertrofiado (también presente en Struthiosaurus transylvanicus) es bastante inusual dentro del grupo, lo que sugiere una coordinación cerebral más sofisticada para la postura y el movimiento, y quizá unos hábitos locomotores más cursoriales que los previstos para otros anquilosaurios.

Palabras clave: Santoniense, Iharkút, Ankylosauria, Hungarosaurus, cráneo, molde endocraneal.

Traducción: los autore

Résumé en Français

Crâne partiel et moulage endocrânien de l'ankylosaure Hungarosaurus du Crétacé supérieur de Hongrie : implications pour la locomotion

Un crâne partiel d'un ankylosaure du Crétacé supérieur (Santonien) de la formation de Csehbánya à Iharkút et un moulage endocrânien pris à partir de ce crâne, sont décrit . La morphologie de l'exoccipital , la région allongée du "cou" du basioccipital , la forme du condyle occipital , et la flexion différente de la moelle par rapport au cerveau antérieur, différencient sans ambiguïté ce specimen du basicrâne de Struthiosaurus ; il est donc attribué à Hungarosaurus sp. Tandis que le moulage endocrânien reflète un cerveau généralement similaires à ceux des autres ankylosaures, le cervelet dorsalement hypertrophié (également présent chez Struthiosaurus transylvanicus) est assez inhabituel pour ce groupe, suggérant une coordination cérébrale de la posture et du mouvement plus sophistiquée, et peut-être pouvait courir plus que prévu pour les autres ankylosaures.

Mots-clés: Santonien, Iharkút, Ankylosauria, Hungarosaurus, crâne, moulage endocrânien

Translator: Kenny J. Travouillon

Deutsche Zusammenfassung

Schädelteil und endocranialer Ausguss des ankylosaurides Dinosauriers Hungarosaurus aus der späten Kreide von Ungarn: Auswirkungen auf die Lokomotion

Ein teilweise erhaltener ankylosaurider Schädel aus der oberkretazischen (Santon) Csehbánya Formation in Iharkút und dessen endocranialer Ausguss werden beschrieben. Die Morphologie des Exoccipitale, die verlängete „Hals" –Region des Basioccipitale, die Form des Occipitalcondylus und die unterschiedliche Flexur der Medulla relativ zum Vorhirn unterscheiden dieses Stück unzweifelhaft von dem Basicranium von Struthiosaurus , daher wird es Hungarosaurus sp. zugeschlagen. Während der endocraniale Ausguss ein Gehirn, allgemein ähnlich denen anderer Ankylosaurier, widerspiegelt, ist das dorsal hypertrophierte Cerebellum (ebenso vorhanden bei Struthiosaurus transylvanicus) ziemlich unüblich für diese Gruppe. Es weist auf eine entwickeltere cerebrale Koordination von Gang und Bewegnung hin und möglicherweise auf eine mehr cursoriale Bewegugsweise als für andere Ankylosaurier vorhergesagt.

SCHLÜSSELWÖRTER: Santon, Iharkút, Ankylosauria, Hungarosaurus, Schädel, endocranialer Ausguss

Translator: Eva Gebauer

Arabic

405 arab

Translator: Ashraf M.T. Elewa

 

 

Figure 1. (1) Location map of the Iharkút vertebrate locality (Upper Cretaceous [Santonian] Csehbánya Formation, Bakony Mts, western Hungary). (2) Schematic section of the open-pit Iharkút (after Ősi and Mindszenty, 2009). The black arrow indicates the position of the bone-yielding beds that, among other fossils, provided the fragmentary skull referred to Hungarosaurus sp. (in this work) and the associated Hungarosaurus skeletons. (3) The Iharkút locality from a bird's eye view. Asterisk marks the site where the fragmentary skull was found.

figure 1

Figure 2. Fragmentary skull (PAL 2013.23.1) and its CT scan visualisation referred to Hungarosaurus sp. from the Upper Cretaceous (Santonian) Csehbánya Formation, Iharkút, western Hungary. (1–2) right lateral; (3–4) left lateral; (5–6) ventral view. Scale bar is 2 cm. For abbreviations see text.

figure 2

Figure 3. Fragmentary skull (PAL 2013.23.1) and its CT scan visualisation referred to Hungarosaurus sp. from the Upper Cretaceous (Santonian) Csehbánya Formation, Iharkút, western Hungary. (1–2) anterior; (3–4) posterior; (5–6) dorsal view. Scale bar is 2 cm. For abbreviations see text.

figure 3

Figure 4. CT slices through the fragmentary skull (PAL 2013.23.1) referred to Hungarosaurus sp. from the Upper Cretaceous (Santonian) Csehbánya Formation, Iharkút, western Hungary. (1–2) axial slice through the basisphenoid; (3–4) parasagittal slice through the openings of the posterior cranial nerves.

figure 4

Figure 5. Topographic drawing of a silicone rubber mould of the endocranial cavity taken from the braincase of Hungarosaurus sp. (PAL 2013.23.1). (1) dorsal; (2) right lateral; (3) ventral view. Scale bar is 2 cm. For abbreviations see text.

figure 5

Figure 6. Comparison of ankylosaur endocasts in left lateral view. (1) cf. Polacanthus sp. (inverted image; redrawn from Norman and Faiers, 1996); (2) Euoplocephalus sp. (redrawn from Coombs, 1978a); (3) Struthiosaurus transylvanicus (redrawn from Pereda Suberbiola and Galton, 1994); (4) Struthiosaurus austriacus (redrawn from Pereda Suberbiola and Galton, 1994); (5) Hungarosaurus sp. (reversed image); (6) Panoplosaurus mirus (modified from Witmer and Ridgely, 2008). Note the hypertrophied cerebellum in Struthiosaurus transylvanicus and Hungarosaurus sp. Scale bars are 2 cm. For abbreviations see text.

figure 6

 

attilaAttila Ősi
Hungarian Academy of Sciences – Eötvös Loránd University
Lendület Dinosaur Research Group
Pázmány Péter sétány 1/c
Budapest, 1117
Hungary
This email address is being protected from spambots. You need JavaScript enabled to view it.

Attila Ősi is a paleontologist and completed his PhD at the Eötvös Loránd University in Budapest. His current research interests are functional morphology in Mezozoic archosaurs and European Late Cretaceous paleobiogeography.

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peredaXabier Pereda Suberbiola
Universidad del País Vasco/Euskal Herriko Unibertsitatea
Facultad de Ciencia y Tecnología
Dpto. Estratigrafía y Paleontología
Apartado 644
48080 Bilbao
Spain
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Xabier Pereda Suberbiola has a permanent research position at the Universidad del País Vasco/Euskal Herriko Unibertsitatea (Bilbao). Most of his research projects are devoted to Mesozoic Vertebrate Palaeontology, more specifically dinosaurs.

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idesTamás Földes
Institute of Diagnostic Imaging and Radiation Oncology of the University of Kaposvár
Kaposvár
7400 Guba S. 40
Hungary
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Tamás Földes is a geologist completed his MSc at the Eötvös Loránd University in Budapest in 1979. Being a colleague of the Institute of Diagnostic Imaging and Radiation Oncology of the University of Kaposvár, Hungary, his main field of interest is the work with different non-destructive analyses applied in reservoir geology, petrology and paleontology.

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TABLE 1. Cranial measurements (in mm) of Hungarosaurus and Struthiosaurus. Data for Struthiosaurus specimens taken from Pereda Suberbiola and Galton (1994). ?+' indicates that in that case of measurement the specimen is not complete or compressed.

 

Measurements

Hungarosaurus sp. (MTM PAL 2013.23.1)

Struthiosaurus austriacus (PIUW 2349/6)

Struthiosaurus transylvanicus (NHMUK R4966)

Skull length (preserved)

+115

+54

+115

Maximum skull width behind the orbits

-

-

255

Breadth of paroccipital processes

-

-

113

Depth from skull roof to base of basipterygoid process

-

-

114

Transverse diameter of occipital condyle

29.5

21

24

Greatest diameter of foramen magnum

+19

17

18

Breadth of basipterygoid processes

-

+18

35

Height from base of occipital condyle to skull roof

80

56

81

Angle of basisphenoid relative to occipial condyle

95°

105°

-

 

TABLE 2. List of ankylosaur endocranial cast specimens. 

 

Taxon

Material (braincase)

Provenance

References

Euoplocephalus tutus

AMNH 5337

AMNH 5403

AMNH 5405, UALVP 31, 47977

Campanian, Alberta, CA

Coombs (1978a), Hopson (1979)

Witmer and Ridgely (2008)

Miyashita et al. (2011)

Panoplosaurus mirus

ROM 1215

Campanian, Alberta, CA

Witmer and Ridgely (2008)

Struthiosaurus transylvanicus

NHMUK R4966

Maastrichtian, Romania

Nopcsa (1929),

Pereda Suberbiola and Galton (1994)

Struthiosaurus austriacus

PIUW 2349/6

Campanian, Austria

Pereda Suberbiola and Galton (1994)

Cf. Polacanthus foxii

CAMSM X26242

Barremian, UK

Norman and Faiers (1996)

Cedarpelta bilbeyhallorum

CEUM 10267, 12360

Albian-Cenomanian, USA

Carpenter et al. (2001)

"Hokkaido nodosaurid"

MCM A522

Cenomanian, Japan

Hayakawa et al. (2005)

Hungarosaurus sp.

MTM PAL 2013.23.1

Santonian, Hungary

This work