Las Hoyas was an inland lacustrine environment which presents an important aquatic and terrestrial flora (with many specimens of Charophytes, Montsechia, Weischelia or Frenelopsis) and diverse fauna, with specimens of at least five or six Phyla: Arthropods, Molluscs, Chordata and many vermiform soft bodied animals which might be Nemertines or Annelids.
The name from Greek προ (pro-) = "before" and Articulata, i.e. prior to animals with true segmentation such as annelids and arthropods.