from the Mississippian (≈325 Myr, Carboniferous) to the end of the Permian, when
they may have become extinct (Payne et al. 2012), although, there is an alternative
hypothesis (Leven 2010) that the primitive fusulinids, which gave rise to the
superorder Fusulinoida, did not go extinct, but survived through transformation into
more progressive taxa.
The success of Fusulinida in the Palaeozoic most likely was a result of their
acquisition of a calcareous test. This test was primitively homogeneously microgranular and consisted of low-magnesium calcite. In advanced forms the test was
larger (up to 15 cm) and had two or more differentiated layers. Fusulinines are
among the largest single-celled protists preserved in fossil deposits, and provide
perhaps the best-known case of evolution towards large size (Newell 1949; Payne
et al. 2009, 2012). They are usually recorded in limestone sediments (Gallagher
1998; Leven and Gorgij 2011), and thus, probably had easy access to calcium-rich
sea water as a resource for test construction.
In the Palaeozoic a variety of other ostracod-like groups of arthropods cooccurred with ostracods. Bradoriida, Phosphatocopida and Leperditicopida, are all
characterised by having a calcified, bivalved carapace, but their systematic position
remains unclear. The oldest carapaces of ostracods (Palaeocopida) are found in the
early Ordovician (Williams et al. 2008). Early myodocopes appeared in the Silurian,
but because of their poorly mineralised valves the early fossil record of this group is
sparse (Siveter 2008). Podocopes were common in the Palaeozoic, with hundreds of
species recorded, even in the Ordovician (Siveter and Curry 1984; Siveter 2008).
Most of them are known from carapaces only, but rare examples of exceptionally
preserved ostracods with soft body parts are known from the Mesozoic and younger
deposits (Smith 2000; Siveter 2008). It is notable that the first non-marine ostracods
were Podocopes. The systematic position of Palaecopida is still under debate, but
they were a common and widespread ostracod-like group in the Palaeozoic (Gray
1988). Siveter (2008) claims that soft part anatomy of Nymphatelina gravida is
similar to that of myodocopes, and it is possible that Palaeocopida may be an
artificial group. Currently their distinctive valve morphology distinguishes them
from other ostracod taxa (Siveter 2008; Siveter et al. 2010).
Marine invertebrates invaded non-marine environments multiple times since the
Cambrian. Most probably the first major colonisation occurred during the Devonian-Carboniferous transition. The first brackish/freshwater habitats were nearshore, marine embayments or shallow, deltaic lagoons influenced by marine
transgression events (Tibert and Scott 1999; Bennett et al. 2012). The first nonmarine invaders were probably highly tolerant euryhaline species, capable of
thriving in marginal marine environments with varying salinity regimes.
Tibert and Scott (1999) documented the early Carboniferous ostracods and
foraminiferans of Horton Bluff Formation in Maritimes Basin (Nova Scotia,
Atlantic Canada). This environment was interpreted as a restricted marine
embayment that turned brackish. The marginal marine bay fauna was dominated by
an assemblage of euryhaline marine ostracod species Copelandella novascotica,
Cavellina sp., Geisina sp. and opportunistic paraparchitacean ostracods (Shemonaella scotoburdigalensis, S. tatei and Chamishaella sp.). The coastal pond was
94
A. Iglikowska and J. Pawłowska
they may have become extinct (Payne et al. 2012), although, there is an alternative
hypothesis (Leven 2010) that the primitive fusulinids, which gave rise to the
superorder Fusulinoida, did not go extinct, but survived through transformation into
more progressive taxa.
The success of Fusulinida in the Palaeozoic most likely was a result of their
acquisition of a calcareous test. This test was primitively homogeneously microgranular and consisted of low-magnesium calcite. In advanced forms the test was
larger (up to 15 cm) and had two or more differentiated layers. Fusulinines are
among the largest single-celled protists preserved in fossil deposits, and provide
perhaps the best-known case of evolution towards large size (Newell 1949; Payne
et al. 2009, 2012). They are usually recorded in limestone sediments (Gallagher
1998; Leven and Gorgij 2011), and thus, probably had easy access to calcium-rich
sea water as a resource for test construction.
In the Palaeozoic a variety of other ostracod-like groups of arthropods cooccurred with ostracods. Bradoriida, Phosphatocopida and Leperditicopida, are all
characterised by having a calcified, bivalved carapace, but their systematic position
remains unclear. The oldest carapaces of ostracods (Palaeocopida) are found in the
early Ordovician (Williams et al. 2008). Early myodocopes appeared in the Silurian,
but because of their poorly mineralised valves the early fossil record of this group is
sparse (Siveter 2008). Podocopes were common in the Palaeozoic, with hundreds of
species recorded, even in the Ordovician (Siveter and Curry 1984; Siveter 2008).
Most of them are known from carapaces only, but rare examples of exceptionally
preserved ostracods with soft body parts are known from the Mesozoic and younger
deposits (Smith 2000; Siveter 2008). It is notable that the first non-marine ostracods
were Podocopes. The systematic position of Palaecopida is still under debate, but
they were a common and widespread ostracod-like group in the Palaeozoic (Gray
1988). Siveter (2008) claims that soft part anatomy of Nymphatelina gravida is
similar to that of myodocopes, and it is possible that Palaeocopida may be an
artificial group. Currently their distinctive valve morphology distinguishes them
from other ostracod taxa (Siveter 2008; Siveter et al. 2010).
Marine invertebrates invaded non-marine environments multiple times since the
Cambrian. Most probably the first major colonisation occurred during the Devonian-Carboniferous transition. The first brackish/freshwater habitats were nearshore, marine embayments or shallow, deltaic lagoons influenced by marine
transgression events (Tibert and Scott 1999; Bennett et al. 2012). The first nonmarine invaders were probably highly tolerant euryhaline species, capable of
thriving in marginal marine environments with varying salinity regimes.
Tibert and Scott (1999) documented the early Carboniferous ostracods and
foraminiferans of Horton Bluff Formation in Maritimes Basin (Nova Scotia,
Atlantic Canada). This environment was interpreted as a restricted marine
embayment that turned brackish. The marginal marine bay fauna was dominated by
an assemblage of euryhaline marine ostracod species Copelandella novascotica,
Cavellina sp., Geisina sp. and opportunistic paraparchitacean ostracods (Shemonaella scotoburdigalensis, S. tatei and Chamishaella sp.). The coastal pond was
94
A. Iglikowska and J. Pawłowska