Q:Information:  - Acanthostega (meaning "spiny roof") is an extinct genus of stem-tetrapod, among the first vertebrate animals to have recognizable limbs. It appeared in the late Devonian period (Famennian age) about 365 million years ago, and was anatomically intermediate between lobe-finned fishes and those that were fully capable of coming onto land.  - The Carboniferous is a geologic period and system that spans 60 million years from the end of the Devonian Period million years ago (Mya), to the beginning of the Permian Period, Mya. The name "Carboniferous" means "coal-bearing" and derives from the Latin words "carb" ("coal") and "fer" ("I bear, I carry"), and was coined by geologists William Conybeare and William Phillips in 1822. Based on a study of the British rock succession, it was the first of the modern 'system' names to be employed, and reflects the fact that many coal beds were formed globally during that time. The Carboniferous is often treated in North America as two geological periods, the earlier Mississippian and the later Pennsylvanian.  - Eogyrinus attheyi ( from Greek eos , meaning `` dawn '' , and gyrinos , meaning `` tadpole '' ) was one of the largest Carboniferous tetrapods , and perhaps one of the largest of its family , Eogyrinidae , at 4.6 metres ( 15 ft ) in length . Eogyrinus appears to have been a powerful swimmer that moved quickly through the water by swishing its long tail from side to side . It may have been a predator , lying in wait for prey in much the same way as a modern crocodile . It was a lightly built animal , weighing around 560 kilograms ( 1,230 lb ) . Although probably better at hunting in the water , Eogyrinus could probably have also made a grab for prey passing close by on land . Fossils of Eogyrinus are known from northern England . Recent studies by Jennifer A. Clack suggest that the amphibian Pholiderpeton described by Thomas Henry Huxley in 1869 is the same animal as Eogyrinus . If this is so , then Pholiderpeton 's name takes priority .  - Latin (Latin: ) is a classical language belonging to the Italic branch of the Indo-European languages. The Latin alphabet is derived from the Etruscan and Greek alphabets.  - The superclass Tetrapoda (Ancient Greek s tetrapods, "four-footed"), or the tetrapods , comprises the first four-limbed vertebrates and their descendants, including the living and extinct amphibians, birds, mammals, reptiles and some ancient, exclusively aquatic creatures such as the Acanthostega. Tetrapods evolved from the lobe-finned fishes around 390 million years ago in the middle Devonian Period, with modern tetrapod groups having appeared by the late Devonian, 367.5 million years ago. The specific aquatic ancestors of the tetrapods, and the process by which land colonization occurred, remain unclear, and are areas of active research and debate among palaeontologists at present.  - Eogyrinidae is an extinct family of large, long-bodied tetrapods that lived in the rivers of the Late Carboniferous period.    What object entity has the relation of 'taxon rank' with the subject 'eogyrinus'?   Choices: - branch  - family  - genus  - superclass
A:
genus