For the first time, HMG domain sequences from non-bilaterian phyla (Calcispongia, Demospongiae, Ctenophora and Cnidaria) have been included in a phylogenetic study of the SOX family. ❋ Unknown (2008)
Further studies showed that cnidarians used other genes from the bilaterian tool kit. ❋ Unknown (2008)
Among the completely sequenced bilaterian genomes, only the vertebrates have a higher number of SOX genes (e.g., 20 genes in H. sapiens and M. musculus, 24 genes in F. rubripes). ❋ Unknown (2008)
The same genes that patterned the front and back of the bilaterian embryo, for example, were produced on opposite sides of the anemone embryo. ❋ Unknown (2008)
OK we have all bilaterian animals - that is the animals which have an axis of symmetry running down the middle. ❋ Unknown (2009)
Complex embryos displaying bilaterian characters from Precambrian ❋ Unknown (2009)
Still, one can conceptually talk about different stages of life's history, such as the OOL, the last universal common ancestor, the origin of the eukaryotic cell, the first multicellular organisms, the later bilaterian ancestor, the establishment of the modern animal phyla, and all the way down to modern speciation. ❋ Unknown (2006)
"Because all three main clades of bilaterian animals express a let-7 RNA that is temporally regulated, but cnidarian, poriferan and all non-animal species that we analysed do not express a detectable let-7 RNA, we propose that the gene evolved after the divergence of diploblastic and bilaterian animals" ❋ James F. McGrath (2008)
The last common ancestor of all bilaterian animals was a worm, and we can see that ancestry in the organization of most animals today, even when it is obscured by odd little geegaws, like limbs and armor and regional specializations and various dangly spiky jointed bits. ❋ Unknown (2007)
This animal is not descended from that bilaterian worm we take for granted, at any rate. ❋ Unknown (2007)
…But if we sum all the assertions of this sort we produce an impossible and illogical image of the bilaterian common ancestor. ❋ Unknown (2005)
In response to this paradox the Hox paradox, an almost automatic response has been that though they may look different these body parts are actually homologous; that there are basic and still hidden pattern formation processes underlying their development, and that these were already present in the bilaterian common ancestor. ❋ Unknown (2005)
The presence of genomic complexity, right at the dawn of bilaterian animal life [i.e., animals with bilateral symmetry], is inescapable. ❋ Unknown (2010)
Though genes of this family have been reported in a sponge and a cnidarian, the expression patterns and functions of the Lhx family during development in non-bilaterian phyla are not known. ❋ Unknown (2010)
The same data imply that all Precambrian bilaterians ranged in size from the microscopic to the barely visible, and that the Cambrian boundary marks a real and geologically sudden appearance of both large complex bilaterian body fossils, and a major change in the size and complexity of their tracks and trails … recent discovery showed that Precambrian trail fossils do not necessarily indicate the presence of multi-cellular organisms. ❋ Unknown (2009)
[Precambrian] benthic tracks and trails (but no body fossils) that could not have been made by the sessile or planktonic Ediacaran organisms and have, by consensus of all experts, been regarded as bilaterian in origin. ❋ Unknown (2009)
What this all means is that we've got a slightly better picture of what genes were present in the ancestral bilaterian animal. ❋ Unknown (2009)
Combined with the fact that nodal and Pitx are also expressed on the right side in sea urchins, this raises the possibility that the bilaterian ancestor had left-right asymmetry controlled by nodal and Pitx expressed on the right side of the body. ❋ Unknown (2009)
