The fossils of the hughmilleriids have been found in Silurian deposits ranging from the Llandovery to Ludlow epochs in the United States, China and England.
While Hughmilleria lived in brackish and fresh water communities, Herefordopterus was present in a benthic (at the lowest level of water) environment near an intertidal sandy shore and intertidal sandy mudflat environments.

The Silurian deposits of the Pittsford Shale Member in which fossils of Hughmilleria socialis have been found shelter various faunas of eurypterids, including Mixopterus multispinosus, Erettoperus osiliensis, Eurypterus pittsfordensis and Carcinosoma spiniferus, among others.
In the other hand, the Late Silurian of Herefordshire, where most of the fossils of Herefordopterus have been discovered, was home to a wide array of different eurypterids, like Erettopterus gigas, Eurypterus cephalaspis, Nanahughmilleria pygmaea, Marsupipterus sculpturatus, Salteropterus abbreviatus and potentially Slimonia (depending on the identity of S. stylops).
The fossils of the hughmilleriids have been found in Silurian deposits ranging from the Llandovery to Ludlow epochs in the United States, China and England. While Hughmilleria lived in brackish and fresh water communities, Herefordopterus was present in a benthic (at the lowest level of water) environment near an intertidal sandy shore and intertidal sandy mudflat environments.
The Silurian deposits of the Pittsford Shale Member in which fossils of Hughmilleria socialis have been found shelter various faunas of eurypterids, including Mixopterus multispinosus, Erettoperus osiliensis, Eurypterus pittsfordensis and Carcinosoma spiniferus, among others. In the other hand, the Late Silurian of Herefordshire, where most of the fossils of Herefordopterus have been discovered, was home to a wide array of different eurypterids, like Erettopterus gigas, Eurypterus cephalaspis, Nanahughmilleria pygmaea, Marsupipterus sculpturatus, Salteropterus abbreviatus and potentially Slimonia (depending on the identity of S. stylops).
Hughmilleriidae