A Carboniferous Non-Onychophoran Lobopodian Reveals Long-Term Survival of a Cambrian Morphotype

Zoological Institute and Museum, Department of Cytology and Evolutionary Biology, University of Greifswald, Soldmannstrasse 23, 17487 Greifswald, Germany. Electronic address: .
Current Biology (Impact Factor: 9.92). 08/2012; 22(18):1673-5. DOI: 10.1016/j.cub.2012.06.066
Source: PubMed

ABSTRACT Lobopodians, a nonmonophyletic assemblage of worm-shaped soft-bodied animals most closely related to arthropods, show two major morphotypes: long-legged and short-legged forms. The morphotype with stubby, conical legs has a long evolutionary history, from the early Cambrian [1] through the Carboniferous [2, 3], including the living onychophorans and tardigrades [4-6]. Species with tubular lobopods exceeding the body diameter have been reported exclusively from the Cambrian [7-12]; the three-dimensionally preserved Orstenotubulus evamuellerae from the uppermost middle Cambrian "Orsten" (Sweden) is the youngest long-legged lobopodian reported thus far [8]. Here we describe a new long-legged lobopodian, Carbotubulus waloszeki gen. et sp. nov., from Mazon Creek, Illinois, USA (∼296 million years ago) [13]. This first post-Cambrian long-legged lobopodian extends the range of this morphotype by about 200 million years. The three-dimensionally preserved specimen differs significantly from the associated short-legged form Ilyodes inopinata [2], of which we also present new head details. The discovery of a Carboniferous long-legged lobopodian provides a more striking example of the long-term survival of Cambrian morphotypes than, for example, the occurrence of a Burgess Shale-type biota in the Ordovician of Morocco [14] and dampens the effect of any major extinction of taxa at the end of the middle Cambrian [15, 16].

Download full-text


Available from: Georg Mayer, Jul 05, 2015
1 Follower
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This review summarizes some major events in the evolution of body plans along the backbone of the arthropod tree, with a special focus on the origin of insects. The incompatibility among recent molecular phylogenies motivates a discussion about possible causes for failures: there is a worrisome lack of information in alignments, which can be visualized with spectra of split-supporting positions, and there are systematic errors occurring even when using correct models in maximum likelihood methods (Kück et al, this book). Currently, these problems cannot be avoided. Combining information from the fossil record and from extant arthropods, the morphology-based evolutionary scenario leads from worm-like stem-lineage arthropods via first euarthropods to the crown group of Mandibulata. The evolution of the mandibulate head is well documented in the Cambrian Orsten fossils. The evolution within crustaceans is also the evolution that leads to characters of the bauplan of myriapods and insects. It is argued that morphologically myriapods do not fit to the base of the mandibulatan tree and that this placement is also not plausible from a paleontological point of view. Available morphological evidence suggests that myriapods are the sistergroup to Hexapoda and that tracheates evolved from a marine ancestor that was similar in many ways to Remipedia. In the extant fauna, the Remipedia are the sistergroup of Tracheata.
    Deep Metazoan Phylogeny: The Backbone of the Tree of Life, 1 edited by J.W. Wägele, T. Bartolomaeus, 02/2014: chapter Arthropod phylogeny and the origin of Tracheata (= Atelocerata) from Remipedia-like ancestors.: pages 285-341; DeGruyter., ISBN: 9783110262636
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Extant representatives of Onychophora (velvet worms) have been classified into two major subgroups or families, the Peripatidae and the Peripatopsidae. According to our previous estimate, a total of 179 nominal species and twelve additional infraspecific taxa of Onychophora had been described, including numerous “subspecies”, “variations” and “mutations (Mayer & Oliveira 2011). However, the validity of most of these taxa was uncertain. Since this last estimate, a comprehensive world checklist of Onychophora has been published, along with a revision of the nomenclatural status of names (Oliveira et al. 2012a). This study revealed that many previous synonyms and infraspecific taxa might constitute valid species. At the same time, it also has shown that ~10% of the described species of Onychophora show major taxonomical problems and therefore should be regarded as nomina dubia, following the provisions of the International Code of Zoological Nomenclature (ICZN 1999).
    Zootaxa 08/2013; 3703(1):15–16. DOI:10.11646/zootaxa.3703.1.5 · 1.06 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Low character variation among onychophoran species has been an obstacle for taxonomic and phylogenetic studies in the past, however we have identified a number of new and informative characters using morphological, molecular, and chromosomal techniques. Our analyses involved a detailed examination of Epiperipatus biolleyi from Costa Rica, Eoperipatus sp. from Thailand, and a new onychophoran species and genus from Costa Rica, Principapillatus hitoyensisgen. et sp. nov.. Scanning electron microscopy on embryos and specimens of varying age revealed novel morphological characters and character states, including the distribution of different receptor types along the antennae, the arrangement and form of papillae on the head, body and legs, the presence and shape of interpedal structures and fields of modified scales on the ventral body surface, the arrangement of lips around the mouth, the number, position and structure of crural tubercles and anal gland openings, and the presence and shape of embryonic foot projections. Karyotypic analyses revealed differences in the number and size of chromosomes among the species studied. The results of our phylogenetic analyses using mitochondrial COI and 12S rRNA gene sequences are in line with morphological and karyotype data. However, our data show a large number of unexplored, albeit informative, characters in the Peripatidae. We suggest that analysing these characters in additional species would help unravel species diversity and phylogeny in the Onychophora, and that inconsistencies among most diagnostic features used for the peripatid genera in the literature could be addressed by identifying a suite of characters common to all peripatids.
    PLoS ONE 12/2012; 7(12):e51220. DOI:10.1371/journal.pone.0051220 · 3.53 Impact Factor