Exceptional preservation of mid-Cretaceous marine arthropods and the evolution of novel forms via heterochrony.
Sci Adv
; 5(4): eaav3875, 2019 04.
Article
in En
| MEDLINE
| ID: mdl-31032408
ABSTRACT
Evolutionary origins of novel forms are often obscure because early and transitional fossils tend to be rare, poorly preserved, or lack proper phylogenetic contexts. We describe a new, exceptionally preserved enigmatic crab from the mid-Cretaceous of Colombia and the United States, whose completeness illuminates the early disparity of the group and the origins of novel forms. Its large and unprotected compound eyes, small fusiform body, and leg-like mouthparts suggest larval trait retention into adulthood via heterochronic development (pedomorphosis), while its large oar-like legs represent the earliest known adaptations in crabs for active swimming. Our phylogenetic analyses, including representatives of all major lineages of fossil and extant crabs, challenge conventional views of their evolution by revealing multiple convergent losses of a typical "crab-like" body plan since the Early Cretaceous. These parallel morphological transformations may be associated with repeated invasions of novel environments, including the pelagic/necto-benthic zone in this pedomorphic chimera crab.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Arthropods
/
Biological Evolution
/
Fossils
Limits:
Animals
Country/Region as subject:
America do norte
/
America do sul
/
Colombia
Language:
En
Journal:
Sci Adv
Year:
2019
Document type:
Article