Which was the family of XXX?
Cyptendoceras
Cyptendoceras is an extinct nautiloid cephalopod included in the family Ellesmeroceratidae that lived in what would be North and South America during the latter part of the Early Ordovician (late Arenig) from about 475 - 472 mya, existing for approximately 3 million years.
Ellesmeroceratidae