neuroanatomy and the body plan paradox.
"We think that as an early deuterostome
this may represent the primitive beginnings of a very diverse range of species, including ourselves," study co-author Simon Conway Morris from the University of Cambridge, said in a (http://www.cam.ac.uk/research/news/bag-like-sea-creature-was-humans-oldest-known-ancestor) statement .
They are wide-spread, occur both in pro- and eukaryotes, in particular in bacteria and are found in some viruses, protozoa, a few insect species and regularly in deuterostome
animals, from echinoderms onward.
Another very primitive stem group of deuterostomes
, called ventulicolians, has also recently been described that might represent the anatomy of organisms near the base of the deuterostome
evolutionary branch that were ancestral to both the chordates and echinoderms.
Of course, eyes are characteristic of the vertebrates in the deuterostome
We recently reported that larval sea stars are capable of complete regeneration of missing body parts, providing a new deuterostome
model for the study of regeneration.
Despite being trained in comparative anatomy, or perhaps because of it, I was distrustful of some of the morphological criteria - for example, diploblastic versus triploblastic, or proterostome versus deuterostome
- used in reconstructing phylogeny.
Analyses of their mitochondrial genome suggest a deuterostome
affinity of the clade (Philippe et al., 2011; Robertson et al., 2017), but large-scale phylogenomic studies suggest that it is a sister group to all other extant bilaterians (Nephrozoa) (Hejnol et al., 2009; Cannon et al., 2016).
Within the deuterostome
clade, however, few animals are capable of complete nervous system regeneration after total neural ablation.
phylogeny and the sister group of the chordates: evidence from molecules and morphology.