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Titanosaur trackways from the Late Cretaceous El Molino Formation of Bolivia (Cal Orck’o, Sucre)

Meyer C. A., Marty D., Belvedere M.

Annales Societatis Geologorum Poloniae

2018

Vol. 88, No. 2

223--241

The Cal Orck’o tracksite is exposed in a quarry wall, approximately 4.4 km NW of Sucre (Department Chuquisaca, Bolivia) in the Altiplano/Cordillera Oriental, in the El Molino Formation (Middle Maastrichtian). Fossiliferous oolitic limestones, associated with large, freshwater stromatolites and nine levels of dinosaur tracks in the El Molino Formation document an open lacustrine environment. The main track-bearing level is almost vertical with a surface area of ~ 65,000 m2. The high-resolution mapping of the site from 1998 to 2015 revealed a total of 12,092 individual dinosaur tracks in 465 trackways. Nine different morphotypes of dinosaur tracks have been documented. Amongst them are several trackways of theropods, ornithopods, ankylosaurs and sauropods, with the latter group accounting for 26% of the trackways. Two different types of sauropod trackways are present. One exhibits speech-bubble-shaped manus impressions that are rotated outwardly and located more outwards than pes prints, and oval to rounded pes imprints with few details, but with a characteristic oval track shape. The second morphotype has more rounded and axially compressed pes imprints and horseshoe-like manus impressions. The manus shows clear impressions of digits I and V The first morphotype with the more rounded manus can be attributed to a derived titanosaur. The second is assigned to the new ichnogenus Calorckosauripus and was probably made by a basal titanosaur. Both sauropod morphotypes exhibit a narrow-gauge and a wide-gauge stance along the same trackway, and therefore the authors suggest that trackway width may not be correlated, or may not be correlated completely with the osteological characters of the trackmaker’s skeleton.

A Late Jurassic diverse ichnocoenosis from the siliciclastic Iouaride`ne Formation (Central High Atlas, Morocco)

Belvedere M., Mietto P., Ishigaki S.

Geological Quarterly

2010

Vol. 54, No 3

367-380

The Late Jurassic Iouaride`ne tracksite has been studied for decades and is well-known for the reference trackway of Breviparopus taghbaloutensis. These siliciclastic flood-plain deposits bear probably more than 1500 tracks, and at least 21 trampled levels: they yield tracks of medium to very large sauropods, possible stegosaurs and theropods. The first accurate description of the footprint association made by biped trackmakers is proposed herein. More than six hundred footprints and more than a hundred trackways has been mapped and analysed; this led to the definition of four tridactyl and two tetradactyl morphotypes, mainly produced by small to very large theropods, while probable small ornithopod tracks are also present. The bipedal footprint association is dominated by medium-large theropods, which are also the most abundant type. The taxonomical attribution of the morphotypes is made difficult by the poor preservation of many specimens. Furthermore, for the most abundant theropod tracks, those with "megalosaurian" affinity, there is also a complex ichnotaxonomical situation, that makes the attributions yet more challenging; however, it was possible to recognize the great affinity of the tridactyl specimens with the Megalosauripus tracks from the Iberian Peninsula and North America. Three-dimensional models were generated from the moulds of the best-preserved specimens to render a more detailed description and for easier access to the specimens.