Morphological Cladistic Analysis as a Model for Character Evaluation in Primitive Living Chitons (Polyplacophora, Lepidopleurina)*

Sigwart, Julia D.

doi:10.4003/006.027.0208

Cited by 31 publications

(26 citation statements)

References 15 publications

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“…CIR molecular clock model estimates the age of crowngroup Polyplacophora to be 357 Ma (408 -298 Ma), and the age of Chitonida was estimated to be 272 Ma (336 -201 Ma). These results conform to the fossil record in which the crown group of Polyplacophora has been estimated to have diverged in the Carboniferous [49] and stem members of Chitonida are known from the Early Permian (Leonardian: 270 -275 Ma) [50]. The concordance between the geological and genetic records for chitons using external calibration points suggests that our molecular clock can be used to estimate divergences deeper within the Aculifera.…”

Section: Results (A) Phylogenetic Analysissupporting

confidence: 72%

A molecular palaeobiological hypothesis for the origin of aplacophoran molluscs and their derivation from chiton-like ancestors

et al. 2011

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Aplacophorans have long been argued to be basal molluscs. We present a molecular phylogeny, including the aplacophorans Neomeniomorpha (Solenogastres) and Chaetodermomorpha (Caudofoveata), which recovered instead the clade Aculifera (Aplacophora þ Polyplacophora). Our relaxed Bayesian molecular clock estimates an Early Ordovician appearance of the aculiferan crown group consistent with the presence of chiton-like molluscs with seven or eight dorsal shell plates by the Late Cambrian (approx. 501 -490 Ma). Molecular, embryological and palaeontological data indicate that aplacophorans, as well as chitons, evolved from a paraphyletic assemblage of chiton-like ancestors. The recovery of cephalopods as a sister group to aculiferans suggests that the plesiomorphic condition in molluscs might be a morphology similar to that found in monoplacophorans.

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Section: Results (A) Phylogenetic Analysissupporting

confidence: 72%

A molecular palaeobiological hypothesis for the origin of aplacophoran molluscs and their derivation from chiton-like ancestors

et al. 2011

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“…C). Fossil evidence suggests that the crown group radiated in the Carboniferous (Sigwart ) about 350 Ma. Molecular clock analyses are congruent with the fossil record and estimate divergences at c. 340 Ma (Vinther et al .…”

Section: The Aculiferamentioning

confidence: 99%

The origins of molluscs

Vinther

2014

Palaeontology

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The interrelationships and evolutionary history of molluscs have seen great advances in the last decade. Recent phylogenetic studies have allowed alternative morphology-based evolutionary scenarios to be tested and, most significantly, shown that the aplacophorans are sister group to polyplacophorans (chitons), corroborating palaeontological and embryological evolutionary scenarios in which aplacophorans are secondarily simplified from a chiton-like ancestor. Aplacophoran morphology therefore does not represent the plesiomorphic condition for molluscs as a whole. The mollusc crown group radiated in the Early Cambrian, and rapidly thereafter, stem lineages to the major molluscan classes emerged: cephalopods, gastropods, bivalves (= pelecypods), monoplacophorans, rostroconchs (inferred stem scaphopods) and aculiferans. This attests to the fast, adaptive radiation of the crown group during the Cambrian explosion. Kimberella from the latest Ediacaran exhibits several molluscan traits, which justifies its position as a molluscan stem-group member, rather than as a more basal Lophotrochozoan. The interrelationships among the conchiferan molluscs are still a matter of contention and require further palaeontological and molecular phylogenetic scrutiny.

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“…Chitons are one of the earliest diverging groups of living mollusks and are often referred to as ''living fossils'' since their body plan has not significantly changed for over 300 million years (Sigwart, 2009). They are typically oval in shape, bilaterally symmetric, and generally range from a few mm to 15 cm in length (Eernisse and Reynolds, 1994).…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional structure of the shell plate assembly of the chiton Tonicella marmorea and its biomechanical consequences

Connors

Ehrlich

Hog

et al. 2012

Journal of Structural Biology

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Morphological Cladistic Analysis as a Model for Character Evaluation in Primitive Living Chitons (Polyplacophora, Lepidopleurina)*

Cited by 31 publications

References 15 publications

A molecular palaeobiological hypothesis for the origin of aplacophoran molluscs and their derivation from chiton-like ancestors

A molecular palaeobiological hypothesis for the origin of aplacophoran molluscs and their derivation from chiton-like ancestors

The origins of molluscs

Three-dimensional structure of the shell plate assembly of the chiton Tonicella marmorea and its biomechanical consequences

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