Iguanodontidae Cope, 1869

Fejfar, Oldřich, Košťák, Martin, Kvaček, Jiří, Mazuch, Martin & Moučka, Michal, 2005, First Cenomanian dinosaur from Central Europe (Czech Republic), Acta Palaeontologica Polonica 50 (2), pp. 295-300 : 297

cf. Iguanodontidae Cope, 1869 ; gen. et sp. indet.

The left femur of the Iguanodontidae gen. et sp. indet. (IGP MZHLZ/2003/1) is well preserved, without any traces of long transport and redeposition ( Fig. 3 ). However, on its surface, bite marks can be observed ( Fig. 4 ). Given the marine/lagoonal palaeoenvironmental context, sharks of different size can be considered as potential scavengers. The bone was found in situ, in a fossiliferous layer. It was fractured and sligtly dislocated in several parts and subsequently reassembled by the discoverer. Originally the distal end of the bone was enclosed in a limonitic concretion, which enabled detailed preservation.

The measurements of the femur: The total length (proximally reconstructed) = 400 mm, distal width = 78 mm, distal diameter = 97 mm, depth of the intercondylar groove = 39 mm; middle width of the diaphysis = 48 mm, middle diameter of the diaphysis = 40 mm.

The shaft of the femur is straight in parasagittal plane and anteroposteriorly slightly compressed, showing in the middle section a subrectangular shape. The posterior surface of the shaft is nearly flat, the anterior one is rather rounded. In the anterior and posterior views, the shaft is gently curved in the transverse plane resulting in a concave medial margin.

The proximal end of the femur is crushed and poorly preserved. Only the separated head of the femur and the greater trochanter can be reattached to the shaft. In proximal view, the femoral head and its neck form an angle of 100–110 ° with the long axis of the shaft. The damaged fragment of the greater trochanter is poorly preserved.

The distal part is transversely oriented, expanded medially to the longitudinal axis. Both laterally compressed distal condyles are oriented nearly in the parasagittal plane, the lateral one extends longer posteriorly, the medial one is shorter. In distal view the lateral condyle is shifted posteriorly, the medial one laterally. The anterior view of the distal part shows in the middle a narrow sharp groove oriented at an angle 15 ° to the shaft. In the posterior view it continues distally into a relatively broader and deeper intercondylar groove oriented at an angle of 20 ° to the shaft. Approximately above the middle of the posteromedial portion of the shaft, the fourth trochanter forms a narrow crest.

The specimen shows immature bone microstucture in the spongy inner zone, without secondary Haversian osteons, and lamellar mature bone histology with Haversian system in the outer layer.

Figures

Fig. 3. Left femur of cf. Iguanodontidae gen. et sp. indet. (Ornithischia, Ornithopoda), IGP MZHLZ/2003/1, in posterior (A), lateral (B), medial (C), anterior (D), and distal (F) views, with transverse cross−section through the femoral shaft (E).

Fig. 4. Details of the surface of the left femur of cf. Iguanodontidae gen. et sp. indet. showing bite marks probably caused by sharks.