Ancestral state reconstruction of ontogeny supports a bilaterian affinity for Dickinsonia

  title={Ancestral state reconstruction of ontogeny supports a bilaterian affinity for Dickinsonia},
  author={David A. Gold and Bruce Runnegar and James G. Gehling and David K Jacobs},
  journal={Evolution \& Development},
Despite numerous attempts, classification of the Precambrian fossil Dickinsonia has eluded scientific consensus. This is largely because Dickinsonia and its relatives are structurally simple, lacking morphological synapomorphies to clarify their relationship to modern taxa. However, there is increasing precedence for using ontogeny to constrain enigmatic fossils, and growth of the type species Dickinsonia costata is well understood. This study formalizes the connection between ontogeny in… 
Quantitative study of developmental biology confirms Dickinsonia as a metazoan
This study demonstrates that Dickinsonia grew via pre-terminal ‘deltoidal’ insertion and inflation of constructional units, followed by a later inflation-dominated phase of growth, contrary to the widely held assumption that DickinsonIA grew via terminal addition of units at the end of the organism bearing the smallest units.
Highly regulated growth and development of the Ediacara macrofossil Dickinsonia costata
It is shown that development in Dickinsonia costata was surprisingly highly regulated to maintain an ovoid shape via terminal addition and the predictable expansion of modules, suggesting that it does not belong within known animal groups, but that it utilized some of the developmental gene networks of bilaterians.
Phylogenetic relationships among the Rangeomorpha: the importance of outgroup selection and implications for their diversification
There is a strong signal for an upright frondose ancestral state for this clade, likely displaying primary branches that were double-sided, nonrotated, with the lower-tiered and recumbent forms being derived members of a single subclade.
Ediacaran developmental biology
  • F. DunnA. LiuP. Donoghue
  • Environmental Science, Geography
    Biological reviews of the Cambridge Philosophical Society
  • 2018
It is concluded, based on the available evidence, that the affinities of the rangeomorphs and the dickinsoniomorphs lie within Metazoa.
The origin of the animals and a ‘Savannah’ hypothesis for early bilaterian evolution
  • G. BuddS. Jensen
  • Environmental Science, Geography
    Biological reviews of the Cambridge Philosophical Society
  • 2017
The subtle remnants of Ediacara‐style taxa within the Cambrian suggest that they remained significant components of Phanerozoic communities, even though at some point their enabling role for bilaterian evolution was presumably taken over by bilaterians or other metazoans.
Following the logic behind biological interpretations of the Ediacaran biotas
Abstract For almost 150 years, megascopic structures in siliciclastic sequences of terminal Precambrian age have been frustratingly difficult to characterize and classify. As with all other areas of
Death march of a segmented and trilobate bilaterian elucidates early animal evolution
Yilingia is an elongate and segmented bilaterian with repetitive and trilobate body units, each of which consists of a central lobe and two posteriorly pointing lateral lobes, indicating body and segment polarity.
The origin of animals: Can molecular clocks and the fossil record be reconciled?
Despite challenges provided by incomplete preservation, a paucity of phylogenetically informative characters, and uncertain expectations of the anatomy of early animals, a number of Neoproterozoic fossils can reasonably be interpreted as metazoans.
Cambrian petalonamid Stromatoveris phylogenetically links Ediacaran biota to later animals
It follows that petalonamids remained an important component of Cambrian marine ecosystems and that the metazoan radiation can be dated to a minimum age of between 558 and 571 myr.
Anatomical and ontogenetic reassessment of the Ediacaran frond Arborea arborea and its placement within total group Eumetazoa
This work was funded by the Natural Environment Research Council, and an Australian Research Council Discovery Grant (DP0453393) to JGG.


A placozoan affinity for Dickinsonia and the evolution of late Proterozoic metazoan feeding modes
It is hypothesized that the affinities of Dickinsonia lie with the Placozoa (Metazoa), an understudied phylum that is widespread in tropical seas worldwide and discusses the potential evolutionary transitions between the main metazoan feeding modes in the context of the emerging molecular phylogeny.
Terminal addition, the Cambrian radiation and the Phanerozoic evolution of bilaterian form
It is argued that terminal addition was the basal condition in Bilateria, and that modification of terminal added was an important component of the rapid Cambrian evolution of novel bilaterian morphology.
The Cambrian Conundrum: Early Divergence and Later Ecological Success in the Early History of Animals
A compilation of the patterns of fossil and molecular diversification, comparative developmental data, and information on ecological feeding strategies indicate that the major animal clades diverged many tens of millions of years before their first appearance in the fossil record.
Improved Phylogenomic Taxon Sampling Noticeably Affects Nonbilaterian Relationships
This work recovers monophyletic Porifera as the sister group to all other Metazoa and suggests that the basal position of the fast-evolving Ctenophora proposed by Dunn et al. was due to LBA and that broad taxon sampling is of fundamental importance to metazoan phylogenomic analyses.
From Vendian to Cambrian: the beginning of morphological disparity of modern metazoan phyla
  • S. Rozhnov
  • Geography
    Russian Journal of Developmental Biology
  • 2010
It is shown that major features of a morphogenetic archetype could be retained from the time the taxon was formed, and probably, an expanded placozoan level of organization can be assumed for most Vendian animals.
The rise of bilaterians
While genera with both kinds of symmetry properties and unitary and colonial animals were present during the early Ediacaran, there was a large proportional increase in new bilaterian genera and a decrease in colonial genera beginning between 560–550 MA.
Error, signal, and the placement of Ctenophora sister to all other animals
Investigating possible causes of systematic error by expanding taxon sampling with eight novel transcriptomes, strictly enforcing orthology inference criteria, and progressively examining potential causes of systemic error while using both maximum-likelihood with robust data partitioning and Bayesian inference with a site-heterogeneous model finds a single, statistically robust placement of ctenophores as the authors' most distant animal relatives.
Testing the protozoan hypothesis for Ediacaran fossils: a developmental analysis of Palaeopascichnus
Developmental analysis of the Palaeopascichnus reveals unusual, protozoan features, including evidence for chaotic repair structures, for mergence of coeval forms, as well as complex bifurcations, which suggest that Palaeobiology is a body fossil of an unidentified protozoa but is unrepresentative of Ediacaran body construction, in general.
The Radiata and the evolutionary origins of the bilaterian body plan.
Wonderful Ediacarans, wonderful cnidarians?
  • D. Erwin
  • Environmental Science
    Evolution & development
  • 2008
In Wonderful Life, Stephen Jay Gould argued that the morphological range of arthropods recovered from the Middle Cambrian Burgess Shale fauna in British Columbia demonstrated that morphologic diversity increased more rapidly than taxonomic diversity, which triggered the development of rigorous empirical approaches to quantifying morphological disparity.