Cotyledion and creationists

Inferno
Inferno
Mon Jul 22, 2013 11:32 am by Inferno

I often search creationist websites for new arguments, but they’re usually the same: “Evolution is wrong because of X, therefore creation”. In addition to that, they haven’t really found new examples for the last five or so years. Since Kitzmiller vs. Dover, there has been surprisingly little from creationists. Even finding a new organism to criticize is a relative novelty for creationists.

So I was surprised to find that the Institute for Creation Research (ICR) had an article up (this was about mid January) criticizing the evolutionary history of Cotyledion tylodes. Now even though this article appears under my name, this is a joint project between Isotelus and me. I wrote it and she heavily criticized and improved it. So, let’s take a look at the ICR article.

Another Cambrian Discovery Discredits Evolution

A fossil creature from the phylum Entoprocta (invertebrate animals that have tentacles and lacking a mineralized skeleton) was found in marked abundance (over 400 individuals) in Burgess Shale. The Burgess is a sedimentary layer that’s purportedly part of the Cambrian period about a half-billion years ago, according to evolutionists.1 The problem for paleontologists is that the supposedly 520 million year old creature looks exactly like its living counterparts, only up to 8 eight times larger.

First, let’s quickly explain what Entoprocta is and where it fits in. They are animals in the superphylum “Lophotrochozoa“, just like we are in the superphylum “Deuterostopmia“. Lophotrochozoa includes Molluscs, Annelids and of course Entoprocta.

Entoprocta differs from the largely similar Bryozoa (or Ectoprocta, archaic) in one major aspect: All Bryozoa have the anus on the outside, while Entoprocta have the anus on the inside. Entoprocta range from the early Cambrian until today, with a fair number of living relatives still around. (Examples include LoxosomatidaeBarentsiidaePedicellinidae and Loxokalypodidae) These represent four families with around 150 species.

One thing to note is that I couldn’t trace C. tylodes to the Burgess Shale (Canada), but rather to Chengjiang in China. Now that’s not a huge problem since both “lagerstätten” are roughly of the same time period. (505mya and 520mya respectively) However, the fossils are significantly closer to the Cambrian Explosion (~550mya) I could also be missing something and this fossil was actually found in the Burgess Shale, but there’s no indication for that. Indeed, Zhang et al. (2013) and Luo et al. (1999, original find) both mention the Chengjiang Konservat-Lagerstätte.

This is another testament to the stunningly thorough research abilities of creationists: The Burgess shale fossil they’re confusing C. tylodes with is Dinomischus, which has an unknown affinity.

But let’s now look at the anatomy. Sadly, the picture provided by LiveScience is incorrectly labelled (Isophagus instead of Esophagus), the original one can be found in Zhang et al. (2013), Figure 1.

Here’s the incorrectly labelled version for better viewing pleasure, the original is too small:

Figure 1.: Extinct Entoprocta, C. tylodes, interpretative drawing

The creationist contention is that C. tylodes look the same as their living relatives. Now I already pointed to the four families above, so we’ll look at a few species. Loxosomella vivipara (apparently now called Loxocalyx raja?), Loxomitra kefersteiniiLoxosomella crassicauda They all look fairly different from C. tylodes, though of course the main structure remains.

A quote from this article is spot on:

Indeed, researchers are coming to realize that the term “living fossil” is a misnomer. One by one, the classic examples—horseshoe crabs, coelacanths, cycads, and more—have turned out to be very different from the fossils that they apparently resemble, either at a genetic level or through subtle physical changes. Their recognizable nature is a red herring—these creatures simply did not exist in their current form millions of years ago.

Let’s recap those last two points: Contrary to the creationists statements, extinct Entoprocta look different than their extant counterparts. But even if they did not change much morphologically, it’s certain that they would have changed genetically.

Now we already know that size isn’t at all relevant when it comes to animals’ and plants’ evolutionary status, but what if C. tylodes really was more complex than his ancestors? That would be a completely different discussion. Now to check that, the only resources available to us are the pictures I provided above and peer-reviewed articles talking about their structures/anatomy/etc.

The pictures already showed some differences, but that doesn’t solve the question of complexity. In the case of C. tylodes, the creationists were very specific in their criticism:

Interestingly, the fossils of C. tylodes also appear to have somewhat more complex features than modern entoprocts. Unlike living entoprocts, the stem and flowerlike feeding cup of the “ancient” version was covered by tiny hardened protuberances (sclerites), and the creatures were much larger.

Now there’s absolutely no denying that the average C. tylodes was much larger than modern Entoprocta, extant ones being between 0.1mm and 7mm, extinct ones between 8mm and 56mm long. I already explained that size really doesn’t matter, so we can safely skip over that point.

So on to the next point: tiny scelerites. This too is true, in fact the 2013 paper (Zhang et al.) is actually called “A scelerite-bearing stem group…” But is that really a sign of complexity? Let’s look at the rest.

Figure 2.: Extant Entoprocta anatomy

This picture shows what extant Entoprocta look like. Well, it’s of course either a general form or one specific species, I couldn’t determine that. (Note: Isotelus suggests it’s most likely a general form.) Notice the tentacles on the left (extended) and on the right (retracted). This is actually a very important quality in this Phylum, because they feed by putting stuff into their mouths with their tentacles. In Zhang et al., they specifically state that C. tylodes was able to retract the tentacles a bit, but not as much as extant Entoprocta.

In addition, there is some evidence that the tentacles may have been contractible and could have been retracted into the membranous band where they originate from (Fig. S4a–c), suggesting some degree of retractability of the tentacles that corresponds functionally and structurally to that seen in those of the extant entoprocts [1].

So C. tylodes was well on its way to retracting them fully, but they don’t seem to have been as mobile as their contemporary counterparts. This may be due to the fossils we found, since none of them exhibit the degree of curling that modern examples do. So on this, the jury is still out. The scelerites mentioned may also be the reason why the tentacles are so well-preserved. Which isn’t at all unexpected, given how well preserved other fossils from that location are.

However, Zhang et al. also note other differences to extant Entoprocta.

In addition, recent entoprocts are pseudocoelomate, with the cavity surrounding the calycal (aka. calyx, see Fig. 2) organs and extending into the stalk in-filled by a hydrostatic skeleton of loose mesenchyme cell or narrow primary body cavity [1].

So there we have it, folks: Extinct Entoprocta were different from their extant descendants and they were almost certainly not as complex. (Whatever creationists mean by that.)

Resources/References:

Clausen, S. B.; Hou, X. G.; Bergström, J.; Franzén, C. (2010). “The absence of echinoderms from the Lower Cambrian Chengjiang fauna of China: Palaeoecological and palaeogeographical implications”. Palaeogeography, Palaeoclimatology, Palaeoecology 294 (3–4): 133.

Iseta, Tohru. (2002) Loxocorone, a New Genus of the Family Loxosomatidae (Entoprocta: Solitaria), with Descriptions of Two New Loxomitra (sensu stricto) and a New Loxocorone from Okinawa, the Ryukyu Archipelago, Japan Toological Science 19: 359–367 (2002)

Luo, Huilin, Hu, Shixue, Chen, Laingzhong, (1999). “Early Cambrian Chengjiang Fauna from Kunming Region, China. Yunnan Science and Technology press, Kunming China. (<–Only in Chinese, if you really want to read it…)

Zhang, Z.; Holmer, L. E.; Skovsted, C. B.; Brock, G. A.; Budd, G. E.; Fu, D.; Zhang, X.; Shu, D. et al. (2013). “A sclerite-bearing stem group entoproct from the early Cambrian and its implications”. Scientific Reports 3

Be Sociable, Share!

    Tags: , ,

    Facebook Auto Publish Powered By : XYZScripts.com