The ENV article quotes the University of Bristol press release as saying:
This image is based on the presence and absence of anatomical features, like jointed legs and compound eyes, neurons and boney skulls. Considering all of these features, animals that are similar group together, far away from animals that are dissimilar. Most of this âdesign spaceâ is unoccupied, in part because of extinction of ancient ancestors that are unrepresented, in part because animals have only been around for half a billion years and that is not enough time to explore all possible designs, but most of the design space is unoccupied because those designs are impossible.
ENVâs response to this is:
Did you hear that right? Ancestors that are âunrepresentedâ? What are those? Apparently, they are potential bodyplans that were never actualized because of limited time for evolution to âexploreâ those parts of âdesign space.â
Apparently the author didnât read the paper. The caption in the press release was describing a single figure that only included extant species as data. So yes, extinct forms were âunrepresentedâ in that particular figure.
Throughout the ENV article the author makes little jibes about the apparent absence of transitional forms that âfill in the gapsâ in morphology:
The paper appears to say that the authors simply imagined animals in the spaces where no remains are known
The âunrepresentedâ forms, therefore, must have appeared, and then disappeared without a trace.
They imagine transitional forms that are âunrepresentedâ in design space, but went extinct, leaving the appearance of gaps.
When you see gaps between the bodyplans, just imagine some intermediate forms that were exploring âshape space,â but went extinct, leaving gaps.
If they had read the paper, they would have found quotes like this one (my emphasis):
Our analyses demonstrate that, even though many (but not all) modern clades occupy discrete regions of morphospace, the inclusion of Cambrian taxa indicates that phylogenetic intermediates of living clades occupy concomitantly intermediate regions of morphospace. Combined with our inferences of the course of metazoan phylogeny through morphospace, these results indicate that the morphological discreteness of modern clades is largely a consequence of the extinction of phylogenetic intermediates.
In other words, including Cambrian fossils in the analysis plugs the gaps in morphospace - the reason phyla appear so discrete from one another today is because the morphologies that connect them are extinct - but we have the fossils.
WRT to this quote from the paper, the ENV article says that they paperâs authors are simply âimaginingâ animal forms:
we coded a phylogenetically diverse and representative sample of Cambrian taxa, principally the earliest representatives of ordinal level clades. This entailed coding 70 fossil taxa for the existing character set and adding 111 mostly autapomorphic characters. Coding these fossil taxa was potentially problematic in that most of the characters (54.1%) are not preserved, and therefore unknown.
However, if we read the paper (notice a trend?), we find that the authors were careful to highlight this point. The quote ENV uses is basically saying that the Cambrian fossils were incompletely preserved, missing half (54.1%) of their phylogenetically informative characters, relative to the extant taxa. They outline 2 ways around this missing data. First, they subsample their entire dataset using just the characters found in the Cambrian fossils, and get the same basic trend, with a few exceptions. These results still indicate that the Cambrian forms âfill in the gapsâ, but the authors are interested in more than that, so theyâre not satisfied with just this. The authors use another technique to infer the missing character states based on their phylogenetic position. This is the part where IDers and creationists shout âHuzzah! Look, theyâre assuming evolution!â However, the authors explain (my emphasis):
There are obviously assumptions inherent in inferring missing data, including missing secondary reversals in soft tissues, the potential of differential evolutionary rates between preservable and nonpreservable characters, or limiting the coded fossil autapomorphies to preservable characteristics. However, given the rarity of reversals of superphylum-level nonfossilizable characters in extant taxa and the observation that autapomorphies contribute little to the construction of the morphospace (SI Appendix, Fig. S3), these assumptions are likely to have a minor impact on the projection of fossil taxa into the morphospace defined by the living species. The approach of inferring missing data likely strengthens the phylogenetic signal in the morphospace. However, a comparison with the taphonomically culled dataset (Fig. 2E) indicates a similar and robust placement of the fossil taxa within morphospace.
The ENV article is nothing but the usual predictable rhetoric, and does nothing to dampen the significance of this new paper.