252
Phylogenetic justification. Poinar (2011) assigned it to Thelasmotidae based on its
morphology, dimensions and host association. He suspects it is closely related to
Cephalobellus.
Minimum age. Biostratigraphic evidence suggest a late Albian to early Cenomanian
age for Burmese amber. Recently, dated zircons suggest a minimum age of
98.17 Ma (Shi et al. 2012).
The oldest record for nematodes exploiting other animals can be traced back to
the Mesozoic with evidence of eggs found in a herbivore coprolite from the Triassic
(Da Silva et al. 2014). The coprolite is usually assigned to a cynodont (Hugot et al.
2014)—although identifying its owner is not straightforward (Francischini et al.
2018). This coprolite contains eggs attributed to Ascarididae (Ascaridoidea,
Ascaridomorpha, Ascaridida) (Da Silva et al. 2014) and overlap in time with the
molecular clock divergence time estimates of Ascaridoidea (Li et al. 2018) based on
the host fossil records. This suggests, in some cases at least, the fossil record may
have value in constraining the initial radiation of terrestrial parasites.
Eggs attributed to Ascaridomorpha are also known from a Lower Cretaceous
coprolite attributed to a theropod dinosaur from Belgium (Poinar and Boucot 2006)
and an Upper Cretaceous coprolite attributed to crocodylians from the Adamantina
Formation of Brazil (Cardia et al. 2018, 2019b). Younger eggs from the Upper
Cretaceous were attributed to Heterocheilidae—they fall just outside the divergence
times estimated by Li et al. (2018) for the crown-group of this lineage.
Node. Ascaridomorpha
Fossil Taxon. Ascarites rufferi
Host. Inferred to a cynodont based on circumstantial evidence.
Fossil Evidence. Egg derived from an Upper Triassic coprolite (Da Silva et al. 2014).
Phylogenetic Justification. No formal phylogenetic analysis was performed but
possession of a round, mammillated surface suggests the assignment of eggs to
Ascarididae (Da Silva et al. 2014).
Minimum age. 236 Ma. Coprolites derive from the Santa Maria Formation at the
Sítio Cortado locality (Pinheiros-Chiniqua Sequence) which is assignable to the
Dinodontosaurus Assemblage Zone (Da Silva et al. 2014). This sequence can be
assigned a minimum age of 236 Ma. derived from dated zircons from the overlying formation and consistent with the biostratigraphic correlation of this sequence
with the Chañares Formation (Francischini et al. 2018).
These Triassic coprolites attributed to cynodonts also contained eggs assigned to
Heteroxynematidae (Hugot et al. 2014) which represent the oldest eggs assigned to
Oxyuridomorpha (= Oxyurida).
Node. Oxyuridomorpha
Fossil Taxon. Paleoxyuris cockburni
Fossil Evidence. Egg derived from an Upper Triassic coprolite (Hugot et al. 2014).
Host. Cynodont? (see Ascaridomorpha).
Phylogenetic Justification. The size, shape and presence of a polar cap speak for
the assignment of fossil eggs to the family Heteroxynematidae (Hugot et al. 2014)
K. De Baets et al.
Phylogenetic justification. Poinar (2011) assigned it to Thelasmotidae based on its
morphology, dimensions and host association. He suspects it is closely related to
Cephalobellus.
Minimum age. Biostratigraphic evidence suggest a late Albian to early Cenomanian
age for Burmese amber. Recently, dated zircons suggest a minimum age of
98.17 Ma (Shi et al. 2012).
The oldest record for nematodes exploiting other animals can be traced back to
the Mesozoic with evidence of eggs found in a herbivore coprolite from the Triassic
(Da Silva et al. 2014). The coprolite is usually assigned to a cynodont (Hugot et al.
2014)—although identifying its owner is not straightforward (Francischini et al.
2018). This coprolite contains eggs attributed to Ascarididae (Ascaridoidea,
Ascaridomorpha, Ascaridida) (Da Silva et al. 2014) and overlap in time with the
molecular clock divergence time estimates of Ascaridoidea (Li et al. 2018) based on
the host fossil records. This suggests, in some cases at least, the fossil record may
have value in constraining the initial radiation of terrestrial parasites.
Eggs attributed to Ascaridomorpha are also known from a Lower Cretaceous
coprolite attributed to a theropod dinosaur from Belgium (Poinar and Boucot 2006)
and an Upper Cretaceous coprolite attributed to crocodylians from the Adamantina
Formation of Brazil (Cardia et al. 2018, 2019b). Younger eggs from the Upper
Cretaceous were attributed to Heterocheilidae—they fall just outside the divergence
times estimated by Li et al. (2018) for the crown-group of this lineage.
Node. Ascaridomorpha
Fossil Taxon. Ascarites rufferi
Host. Inferred to a cynodont based on circumstantial evidence.
Fossil Evidence. Egg derived from an Upper Triassic coprolite (Da Silva et al. 2014).
Phylogenetic Justification. No formal phylogenetic analysis was performed but
possession of a round, mammillated surface suggests the assignment of eggs to
Ascarididae (Da Silva et al. 2014).
Minimum age. 236 Ma. Coprolites derive from the Santa Maria Formation at the
Sítio Cortado locality (Pinheiros-Chiniqua Sequence) which is assignable to the
Dinodontosaurus Assemblage Zone (Da Silva et al. 2014). This sequence can be
assigned a minimum age of 236 Ma. derived from dated zircons from the overlying formation and consistent with the biostratigraphic correlation of this sequence
with the Chañares Formation (Francischini et al. 2018).
These Triassic coprolites attributed to cynodonts also contained eggs assigned to
Heteroxynematidae (Hugot et al. 2014) which represent the oldest eggs assigned to
Oxyuridomorpha (= Oxyurida).
Node. Oxyuridomorpha
Fossil Taxon. Paleoxyuris cockburni
Fossil Evidence. Egg derived from an Upper Triassic coprolite (Hugot et al. 2014).
Host. Cynodont? (see Ascaridomorpha).
Phylogenetic Justification. The size, shape and presence of a polar cap speak for
the assignment of fossil eggs to the family Heteroxynematidae (Hugot et al. 2014)
K. De Baets et al.