Macrogryphosaurus

Macrogryphosaurus was an unusually large basal ornithopod discovered in Neuquén Province, Argentina, within rocks dating to the Coniacian stage of the Late Cretaceous. Measuring approximately six metres in total length, it represents the largest identified member of the clade Elasmaria, an endemic Gondwanan group of ornithischians. The holotype specimen consists of an articulated partial skeleton featuring the vertebral column, ribs, pelvis, and sternum. Like its smaller relative Talenkauen, Macrogryphosaurus possessed thin, flattened mineralised plates situated on the rib cage. These plates may have played a biomechanical role during breathing or added passive rigidity to the rib cage during running. As a bipedal browser, Macrogryphosaurus inhabited river floodplains alongside titanosaurs, megaraptoran predators, and unenlagiine dromaeosaurs, underscoring the ecological importance and diversity of native South American ornithopods prior to the arrival of hadrosaurs.

It is the largest known member of Elasmaria and possessed thin bony plates along its ribcage.

Where and when

Macrogryphosaurus lived in the Late Cretaceous, from 89.8 to 86.3 million years ago (Coniacian age). Its remains come from Argentina, in the Portezuelo Formation.

The numbers

Length 6 m (estimates run from 5.5 to 6.5 m). Mass about 980 kg. Hip height about 1.8 m. That is 3.5 human-lengths, or 0.54 of a double-decker bus. These are estimates from partial skeleton; fields marked estimated by the site are length, mass, first ma, last ma, hip height.

Compare Macrogryphosaurus with a bus Place on the timeline