176
using this method (Table  5.2). Depending on the data used (different molecular
markers and their number—both nuclear and mitochondrial, the number of specimens from each family used for obtaining molecular material) time estimations vary
for indicating the origin of the crown group of six unionoid families. The origin of
Margaritiferidae most commonly is assessed as in Late Cretaceous (~80–93  Ma;
Bolotov et al. 2016, 2017b; Huang et al. 2018) however estimations twice as old
have been made (however, this is not fossil-calibrated; Graf et al. 2015). Unionidae,
which have recently received increased attention, are estimated to appear between
the Early Jurassic and Early Cretaceous (most commonly 177–158  Ma; Bolotov
et  al. 2017a, b; Huang et  al. 2018). Hyriidae most likely appeared between Late
Triassic and Early Jurassic (178–225  Ma; Graf et  al. 2015; Bolotov et  al. 2016;
Santos-Neto et al. 2016; Huang et al. 2018). Members of the superfamily Etherioidea
presumably originated  as early as Early Triassic (Huang et  al. 2018) to Late
Cretaceous (Bolotov et al. 2017b), with Early and Middle Jurassic estimations (Graf
et al. 2015; Bolotov et al. 2016).
5.5 Evolution of Parasitism
Little direct fossil evidence is available to constrain the evolution of parasitism
between unionoids and fishes. According to Boucot and Poinar (2010) the best
evidence to interpret fossil behavior (including the parasite-host relation) requires
both preservation of an organism while doing something allowing for a functional
interpretation (e.g. direct association with its hosts). Fossil data like this exist
Table 5.2 The molecular clock estimates indicating the latest possible date of origin of main
lineages of Unionida
Family
Estimation of earliest origin of crown
group (fossil-calibrated: bold)
References
Margaritiferidae
~175 Ma
93 Ma
~80 Ma
88 Ma
Graf et al. (2015)
Bolotov et al. (2016)
Bolotov et al. (2017b)
Huang et al. (2018)
Unionidae
~175 Ma
125 Ma
177 Ma
158 Ma (Oriental species)
166 Ma
Graf et al. (2015)
Bolotov et al. (2016)
Bolotov et al. (2017a)
Bolotov et al. (2017b)
Huang et al. (2018)
Hyriidae
194 Ma
209 Ma
225 Ma
~110 Ma
178 Ma
Graf et al. (2015)
Bolotov et al. (2016)
Santos-Neto et al. (2016)
Bolotov et al. (2017b)
Huang et al. (2018)
Etherioidea
(Iridinidae + Etheriidae +
Mycetopodidae)
~165 Ma
186 Ma
~100 Ma
251 Ma
Graf et al. (2015)
Bolotov et al. (2016)
Bolotov et al. (2017b)
Huang et al. (2018)
A. Skawina