| The discovery of chemosynthesis-based communities in late 1970s was probably one of the
biggest surprises in the marine biology of 20th century. There are three basic types of
locations where such communities may develop: hydrothermal vents, cold seeps, and
vertebrate falls. Also sunken wood communities are partially chemosynthetically fueled.
Reports of these unusual aggregation of benthic animals in the deep sea prompted
a quest for their counterparts in the fossil record. Soon it has been revealed that
a number of exotic carbonate rocks rich in fossils in otherwise siliciclastic deep
water facies could easily be interpreted as a result of ancient cold seeps’ activity.
Later on also numerous hot vent, whale fall, and sunken wood associations have
been described from the geological past. The earliest-known chemosynthesis-based
association containing metazoan animals has been described from Silurian of Ural
Mountains. This and the other Paleozoic chemosynthesis-based associations are
dominated by worm tubes, mollusks (monoplacophorans, bivalves, and gastropods),
and brachiopods. Nothing is known from the period encompassing Permian and
Triassic and the Mesozoic record of chemosynthesis-based communities starts in
Jurassic. The Lower Jurassic hydrothermal vent association from California consists of
worm tubes, gastropods, and brachiopods which are not really comparable to their
counterparts from Recent chemosynthesis-based communities. First associations
composed of fossils recollecting animals from the Recent chemosynthesis-based
communities appear in Late Jurassic. Oxfordian cold seep deposits from France are
dominated by lucinid bivalves and similar deposits from Tithonian of Alexander
Island in the Antarctic are known to contain lucinids and mass aggregations of
hokkaidoconchids—extinct group of gastropods related to Recent Provannidae. Early
Cretaceous is an epoch of rhynchonellide brachiopod Peregrinella which occurs worldwide
abundantly at hydrocarbon seep sites where it is associated by lucinid and modiomorphid
bivalves, hokkaidoconchids and gastropods which are not clearly related to any
of the groups thriving nowadays in chemosynthesis-based communities. Earliest
report of alleged neomphalid gastropod also comes from the same epoch. In the Late
Cretaceous Peregrinella has disappeared while the bivalves started to dominate cold
seep environments. Apart from large lucinids and still present modiomorphids also
solemyids, thyasirids, and manzanellids became locally abundant. Several taxa
of gastropods known also from Recent chemosynthesis-based communities have
appeared at that time. It includes true provannids, acmaeid limpets, collonins, and
cataegins. Also from the Late Cretaceous earliest-known sunken wood association
containing xylophagainin ship worms has been described. Recently it has been shown
that chemosynthesis-based communities could also develop on Late Cretaceous
plesiosaur falls. Oligocene and Eocene chemosynthesis-based communities are known
from numerous cold seep carbonates and wood and whale fall localities in North
Pacific Region. Earliest occurrences of vesicomyids are known from Oligocene seep
carbonates while earliest mytilids have been reported from from whale and wood falls
from Eocene of the US Pacific Coast. Both groups dominate chemosynthesis-based
communities from Miocene onward. Starting from Miocene the chemosynthesis-based
associations have a modern composition although several groups of mollusks (e.g.
majority of neomphalid gastropods and large symbiotic provannids) extremely
common in Recent hydrothermal vents are still unknown from the fossil record. |