Eocarcinus praecursor Withers, 1932 (Malacostraca, Decapoda, Meiura) is a stem group brachyuran

Scholtz, Gerhard

doi:10.1016/j.asd.2020.100991

Cited by 8 publications

(14 citation statements)

References 45 publications

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“…Silhouettes from PhyloPic (phylopic.org), with fossils based on recent publications. [46,48,49] (B) Artistic reconstruction of partly carcinized Eoprosopon klugi as a facultative scavenger. (C) Artistic reconstruction of uncarcinized Platykotta akaina as a dweller of Triassic bivalve reefs.…”

Section: It Is Unclear Whether the Earliest Crabs Looked Like Crabsmentioning

confidence: 99%

“…In E. praecursor , the second and third pereopods are not fully visible, but have recently been reconstructed as distally simple based on multiple specimens. [ 49 ] The lack of three‐dimensional information about these limbs suggests a crown group meiuran affinity of the species, but cannot reject anomuran affinity. [ 48,49 ] Mounting evidence from the combination of total group brachyuran characters, and the lack of characters shared with crown group brachyuran taxa such as dromiaceans and homolids, together suggest that E. praecursor is a stem group brachyuran.…”

Section: It Is Unclear Whether the Earliest Crabs Looked Like Crabsmentioning

confidence: 99%

“…[ 49 ] The lack of three‐dimensional information about these limbs suggests a crown group meiuran affinity of the species, but cannot reject anomuran affinity. [ 48,49 ] Mounting evidence from the combination of total group brachyuran characters, and the lack of characters shared with crown group brachyuran taxa such as dromiaceans and homolids, together suggest that E. praecursor is a stem group brachyuran. [ 49 ] E. klugi exhibits similar character combinations, such as the carapace grooves, claws, and pleonal posture, [ 46 ] but it is challenging to discern details as there is only one specimen known.…”

Section: It Is Unclear Whether the Earliest Crabs Looked Like Crabsmentioning

confidence: 99%

“…[ 48,49 ] Mounting evidence from the combination of total group brachyuran characters, and the lack of characters shared with crown group brachyuran taxa such as dromiaceans and homolids, together suggest that E. praecursor is a stem group brachyuran. [ 49 ] E. klugi exhibits similar character combinations, such as the carapace grooves, claws, and pleonal posture, [ 46 ] but it is challenging to discern details as there is only one specimen known. Together, these early fossils suggest the common ancestor of E. praecursor , E. klugi , and crown group brachyurans was not fully carcinized, possibly with a relatively wide carapace, a partially bent pleon, and may have lost uropods.…”

Section: It Is Unclear Whether the Earliest Crabs Looked Like Crabsmentioning

confidence: 99%

“…This lobster‐looking and uncarcinized decapod shares features in common with some anomurans, and some that contradict a brachyuran affinity, but it is known from a single specimen and the evidence is not definitive. [ 48,49 ] As with E. praecursor and E. klugi , the ventral morphology is poorly preserved. The original description reported chelate second pereopods, [ 50 ] which creates a contradiction.…”

Section: It Is Unclear Whether the Earliest Crabs Looked Like Crabsmentioning

confidence: 99%

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How to become a crab: Phenotypic constraints on a recurring body plan

2021

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A fundamental question in biology is whether phenotypes can be predicted by ecological or genomic rules. At least five cases of convergent evolution of the crab-like body plan (with a wide and flattened shape, and a bent abdomen) are known in decapod crustaceans, and have, for over 140 years, been known as "carcinization." The repeated loss of this body plan has been identified as "decarcinization." In reviewing the field, we offer phylogenetic strategies to include poorly known groups, and direct evidence from fossils, that will resolve the history of crab evolution and the degree of phenotypic variation within crabs. Proposed ecological advantages of the crab body are summarized into a hypothesis of phenotypic integration suggesting correlated evolution of the carapace shape and abdomen. Our premise provides fertile ground for future studies of the genomic and developmental basis, and the predictability, of the crab-like body form.

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Section: It Is Unclear Whether the Earliest Crabs Looked Like Crabsmentioning

confidence: 99%

Section: It Is Unclear Whether the Earliest Crabs Looked Like Crabsmentioning

confidence: 99%

Section: It Is Unclear Whether the Earliest Crabs Looked Like Crabsmentioning

confidence: 99%

Section: It Is Unclear Whether the Earliest Crabs Looked Like Crabsmentioning

confidence: 99%

Section: It Is Unclear Whether the Earliest Crabs Looked Like Crabsmentioning

confidence: 99%

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How to become a crab: Phenotypic constraints on a recurring body plan

2021

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Morphological convergence from independent crab lineages contributes to the flourishing symbiotic diversity between crabs and branching corals

Ma,

Chen,

Sun

et al. 2024

Coral Reefs

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Morphological diversity in true and false crabs reveals the plesiomorphy of the megalopa phase

Braig,

Haug,

Haug

2024

Sci Rep

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Brachyura and Anomala (or Anomura), also referred to as true and false crabs, form the species-rich and globally abundant group of Meiura, an ingroup of Decapoda. The evolutionary success of both groups is sometimes attributed to the process of carcinization (evolving a crab-like body), but might also be connected to the megalopa, a specific transitional larval phase. We investigate these questions, using outline analysis of the shields (carapaces) of more than 1500 meiuran crabs. We compare the morphological diversity of different developmental phases of major ingroups of true and false crabs. We find that morphological diversity of adults is larger in false crabs than in true crabs, indicating that taxonomic diversity and morphological diversity are not necessarily linked. The increasing morphological disparity of adults of true and false crabs with increasing phylogenetic distance furthermore indicates diverging evolution of the shield morphology of adult representatives of Meiura. Larvae of true crabs also show larger diversity than their adult counterparts, highlighting the importance of larvae for biodiversity studies. The megalopa phase of Meiura appears to be plesiomorphic, as it overlaps between true and false crabs and shows little diversity. Causes may be common evolutionary constraints on a developmental phase specialized for transitioning.

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Eocarcinus praecursor Withers, 1932 (Malacostraca, Decapoda, Meiura) is a stem group brachyuran

Cited by 8 publications

References 45 publications

How to become a crab: Phenotypic constraints on a recurring body plan

How to become a crab: Phenotypic constraints on a recurring body plan

Morphological convergence from independent crab lineages contributes to the flourishing symbiotic diversity between crabs and branching corals

Morphological diversity in true and false crabs reveals the plesiomorphy of the megalopa phase

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