244
helical marginal fibres of branchiobdellidan spermatozoans (Bomfleur
et al. 2015).
Min age. 47.8 Ma. The Cucullaea I Allomember of the La Meseta Formation has
been considered Ypresian (Montes et al. 2013), early Eocene, based on Strontium
isotope chemostratigraphy (Ivany et al. 2008) as well as mammal biostratigraphy
(Reguero et al. 2013). The age of the Ypresian-Lutetian boundary tabulated in
GTS 2016 (Ogg et al. 2016) can therefore be used as a conservative minimum
constraint.
7.4.2 Fossil Record of Parasitic Pentastomids
Pentastomids, or tongue worms, have traditionally been considered to be a separate
phylum, but they are now considered crustaceans—most likely the sister group of
Branchiura (Regier et al. 2010; Sanders and Lee 2010; Oakley et al. 2012; but see
Haug et al. 2021). So far no crown-group Branchiura have been reported from the
fossil record. Dzik (2008) assigned the enigmatic Cyclida (Carboniferous—Triassic)
to Branchiura, but these are free-living (Schram et al. 1997) and their affinities with
modern Branchiura is unlikely (Haug et al. 2021).
The fossil record of Pentastomida has been reviewed by various authors
(Castellani et al. 2011; Klompmaker and Boxshall 2015). Various isolated fossils
from the Cambrian-Ordovician have been identified as larval pentastomids
(Walossek and Müller 1994; Walossek et al. 1994; Waloszek et al. 2005; Castellani
et al. 2011), and due to their morphology these early forms have been interpreted as
being parasitic. They represent the oldest direct evidence for ectoparasitic “worms”
in the fossil record. Their hosts are still debated (De Baets et al. 2015). Most authors
suspect they were parasitizing early vertebrates (Walossek and Müller 1994; Sanders
and Lee 2010), but no direct associations are known. Their hosts must have been
different from current hosts as present day lineages were not around at the time of
the early fossil pentastomids (De Baets et al. 2015). A recent discovery interpreted
as a pentastomid makes interpretations of early life histories even more problematic
as these fossils are interpreted as adult and attached to ostracods—a host relationship so far not observed in present day (Siveter et al. 2015; but see Haug et al. 2021
for an alternative interpretation).
Node. Total Group Pentastomida
Fossil Taxon. Boeckelericambria pelturae
Fossil evidence. Isolated phosphatic remains of larvae in calcareous nodules
Phylogenetic justification. The diagnostic synapomorphy of a head of
Boeckelericambria pelturae with two pairs of grasping hooks (Walossek and
Müller 1994) as well as a cladistic analysis (Waltécio de Oliveira and
Christoffersen 1999) place this species as a stem-group pentastomid. If we accept
Pentastomida to be the sister group of branchiura, B. penturae must therefore
K. De Baets et al.
helical marginal fibres of branchiobdellidan spermatozoans (Bomfleur
et al. 2015).
Min age. 47.8 Ma. The Cucullaea I Allomember of the La Meseta Formation has
been considered Ypresian (Montes et al. 2013), early Eocene, based on Strontium
isotope chemostratigraphy (Ivany et al. 2008) as well as mammal biostratigraphy
(Reguero et al. 2013). The age of the Ypresian-Lutetian boundary tabulated in
GTS 2016 (Ogg et al. 2016) can therefore be used as a conservative minimum
constraint.
7.4.2 Fossil Record of Parasitic Pentastomids
Pentastomids, or tongue worms, have traditionally been considered to be a separate
phylum, but they are now considered crustaceans—most likely the sister group of
Branchiura (Regier et al. 2010; Sanders and Lee 2010; Oakley et al. 2012; but see
Haug et al. 2021). So far no crown-group Branchiura have been reported from the
fossil record. Dzik (2008) assigned the enigmatic Cyclida (Carboniferous—Triassic)
to Branchiura, but these are free-living (Schram et al. 1997) and their affinities with
modern Branchiura is unlikely (Haug et al. 2021).
The fossil record of Pentastomida has been reviewed by various authors
(Castellani et al. 2011; Klompmaker and Boxshall 2015). Various isolated fossils
from the Cambrian-Ordovician have been identified as larval pentastomids
(Walossek and Müller 1994; Walossek et al. 1994; Waloszek et al. 2005; Castellani
et al. 2011), and due to their morphology these early forms have been interpreted as
being parasitic. They represent the oldest direct evidence for ectoparasitic “worms”
in the fossil record. Their hosts are still debated (De Baets et al. 2015). Most authors
suspect they were parasitizing early vertebrates (Walossek and Müller 1994; Sanders
and Lee 2010), but no direct associations are known. Their hosts must have been
different from current hosts as present day lineages were not around at the time of
the early fossil pentastomids (De Baets et al. 2015). A recent discovery interpreted
as a pentastomid makes interpretations of early life histories even more problematic
as these fossils are interpreted as adult and attached to ostracods—a host relationship so far not observed in present day (Siveter et al. 2015; but see Haug et al. 2021
for an alternative interpretation).
Node. Total Group Pentastomida
Fossil Taxon. Boeckelericambria pelturae
Fossil evidence. Isolated phosphatic remains of larvae in calcareous nodules
Phylogenetic justification. The diagnostic synapomorphy of a head of
Boeckelericambria pelturae with two pairs of grasping hooks (Walossek and
Müller 1994) as well as a cladistic analysis (Waltécio de Oliveira and
Christoffersen 1999) place this species as a stem-group pentastomid. If we accept
Pentastomida to be the sister group of branchiura, B. penturae must therefore
K. De Baets et al.