Early Cambrian “Soft-Shelled” Brachiopods as Possible Stem-Group Phoronids

@inproceedings{Balthasar2009EarlyC,
  title={Early Cambrian “Soft-Shelled” Brachiopods as Possible Stem-Group Phoronids},
  author={Uwe Balthasar and Nicholas J. Butterfield},
  year={2009}
}
Brachiopods and phoronids are widely recognised as closely related lophophorate phyla, but the lack of morphological intermediates linking the bivalved bodyplan of brachiopods with tubular phoronids has frustrated precise phylogenetic placement. Here we describe Lingulosacculus nuda gen. et sp. nov., a new “soft-shelled” brachiopod from the Early Cambrian Mural Formation of western Alberta which provides a plausible candidate for a phoronid stem-group within (paraphyletic) Brachiopoda. In… 

An early Cambrian agglutinated tubular lophophorate with brachiopod characters

TLDR
A tubular fossil from the Cambrian of China exhibits an unusual combination of phoronid, brachiopod and tommotiid characters, notably a pair of agglutinated valves, enclosing a horseshoe-shaped lophophore supported by a lower bipartite tubular attachment structure with a long pedicle with coelomic space.

Hyoliths with pedicles illuminate the origin of the brachiopod body plan

TLDR
A new orthothecide hyolith from the Chengjiang Lagerstätte (Cambrian Series 2 Stage 3) is described, which exhibits a non-mineralized attachment structure that strikingly resembles the brachiopod pedicle—the first report of a peduncular organ in hyoliths.

Paterimitra pyramidalis from South Australia: scleritome, shell structure and evolution of a lower Cambrian stem group brachiopod

The tommotiid Paterimitra pyramidalis Laurie, 1986, is redescribed based on well‐preserved material from the lower Cambrian Wilkawillina, Wirrapowie and Ajax limestones of the Flinders Ranges, South

Homologous skeletal secretion in tommotiids and brachiopods

TLDR
It is shown that the shell microstructure of Eccentrotheca and Paterimitra share substantial similarities with paterinid brachiopods, and the organophosphatic skeletal composition as plesiomorphic with calcareous shells as derived.

Orthrozanclus elongata n. sp. and the significance of sclerite-covered taxa for early trochozoan evolution

TLDR
The scleritome arrangement and constitution in this material corroborates the link between Orthrozanclus and Halkieria, but not with Wiwaxia — and calls into question its purported relationship with molluscs.

Hyoliths are Palaeozoic lophophorates

TLDR
This work reconstructs Haplophrentis as a semi-sessile, epibenthic suspension feeder that could use its helens to elevate its tubular body above the sea floor and indicates an affinity with the lophophorates (brachiopods, phoronids and tommotiids), substantially increasing the morphological disparity of this prominent group.

The oldest Cambrian trilobite – brachiopod association in South China

EVOLUTION OF BIOMINERALIZATION IN 'LOPHOPHORATES'

TLDR
It is concluded that biomineral- ized skeletons are not homologous in lophophorates, the skeletons of brachiopods being plesiomorphic, whereasBiomineralization in bryozoans is apomorphic and has evolved independently twice from soft-bodied, ctenostome- grade bryozoan ancestors.

Rerooting the rDNA gene tree reveals phoronids to be ‘brachiopods without shells’; dangers of wide taxon samples in metazoan phylogenetics (Phoronida; Brachiopoda)

TLDR
It is shown that outgroup rooting of brachiopods and phoronid rDNAs is unreliable, and instead the root position is found with procedures that are free from all distortions caused by distantly related taxa, i.e. by Bayesian and maximum likelihood relaxed-clock analyses of a purely ingroup alignment.

Soft-Part Preservation in a Linguliform Brachiopod from the Lower Cambrian Wulongqing Formation (Guanshan Fauna) of Yunnan, South China

Linguliform brachiopods were important components of early Cambrian benthic communities. However, exceptionally preserved soft parts in Cambrian linguliform brachiopods are extremely sparse, and the

References

SHOWING 1-10 OF 63 REFERENCES

A spinose stem group brachiopod with pedicle from the Middle Cambrian Burgess Shale

TLDR
The shells of the new stem group brachiopod are often deformed and do not show signs of brittle breakage, which suggests that the valves were originally either entirely organic in composition or, more likely, had just a minor mineral component.

The Early Cambrian tommotiid Micrina, a sessile bivalved stem group brachiopod

TLDR
A new reconstruction of Micrina shows that a simple type of filter-feeding within an enclosed bivalved shell had started to evolve in derived tannuolinids, and indicates that the phylogenetic range of ‘bivalved’, sessile lophophorates is larger than previously suspected.

The Early Cambrian [Botomian] stem group brachiopod Mickwitzia from Northeast Greenland

TLDR
The late Early Cambrian sequence of North-East Greenland has yielded an assemblage of more than 88 species of small shelly fossils, brachiopods and trilobites, indicative of a middle Dyeran age (Botoman equivalent), and the many cosmopolitan taxa thus identified suggests a close juxtaposition of palaeocontinents at this time.

THE ENIGMATIC EARLY CAMBRIAN SALANYGOLINA– A STEM GROUP OF RHYNCHONELLIFORM CHILEATE BRACHIOPODS?

Abstract:  New material of the enigmatic brachiopod Salanygolina obliqua Ushatinskaya from the Early Cambrian of Mongolia shows that it has a colleplax– a triangular plate – in the umbonal

A Stem Group Brachiopod From The Lower Cambrian: Support For A Micrina (Halkieriid) Ancestry

TLDR
The late Early Cambrian sequence of North-East Greenland has yielded an assemblage of more than 88 species of small shelly fossils, brachiopods and trilobites, indicative of a middle Dyeran age (Botoman equivalent), and the many cosmopolitan taxa thus identified suggests a close juxtaposition of palaeocontinents at this time.

Hooking some stem‐group “worms”: fossil lophotrochozoans in the Burgess Shale

  • N. Butterfield
  • Biology, Environmental Science
    BioEssays : news and reviews in molecular, cellular and developmental biology
  • 2006
TLDR
Analysis of the fossil record of two famously problematic worms, Odontogriphus and Wiwaxia, reveals pronounced anatomical and histological discrepancies with molluscan analogues, such that they are more reliably interpreted as primitive features of the superphylum Lophotrochozoa.

Shell structure, ontogeny and affinities of the Lower Cambrian bivalved problematic fossil Mickwitzia muralensis Walcott 1913

TLDR
Based on the posterior margin and the shell microstructure, a close relationship between Mickwitzia and the paterinids is proposed with differences interpreted as heterochronic.

PHYLOGENETIC RELATIONSHIPS AMONG EXTANT BRACHIOPODS

  • S. Carlson
  • Biology, Environmental Science
    Cladistics : the international journal of the Willi Hennig Society
  • 1995
TLDR
A phylogenetic analysis of the monophyletic status of the Brachiopoda and phylogenetic relationships within the phylum found that arguments concerning single or multiple origins of a bivalved shell are not relevant to recognizing brachiopods as a clade.

The monophyletic origin of the Brachiopoda

TLDR
Cladistic analysis of both living forms and Lower Paleozoic taxa strongly supports the contention that brachiopods are monophytetic and closely related to the phoronids and suggests, however, that the ‘inarticulate’ Paterinida and Kutorginida are genealogically more closely related than they are to the remaining Inarticulata.

An Unusual Micromorphic Brachiopod from the Middle Cambrian of North-Eastern New South Wales, Australia

  • G. Brock
  • Geography, Environmental Science
  • 1999
Anomalocalyx cawoodi new genus and new species, from Middle Cambrian (Floran-Undillan) allochthonous limestone clasts of the Murrawong Creek Formation, north eastern New South Wales, is characterised
...