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Cambrian Arthropod Was a Loving Mother

Waptia-fieldensis-fossil-with-brooded-eggs-highlighted.jpg

An egg clutch has been identified within the carapace of Waptia, an arthropod previously known from the Burgess Shale (Middle Cambrian, dated 508 million years ago). The eggs are highlighted in a photo from the University of Toronto (above), which calls this the "oldest evidence of brood care" in any animal.

Long before kangaroos carried their joeys in their pouches and honey bees nurtured their young in hives, there was the 508-million-year-old Waptia. Little is known about the shrimp-like creature first discovered in the renowned Canadian Burgess Shale fossil deposit a century ago, but recent analysis by scientists from the University of Toronto, Royal Ontario Museum, and Centre national de la recherche scientifique has uncovered eggs with embryos preserved within the body of the animal. It is the oldest example of brood care in the fossil record. [Emphasis added.]

Five examples of the egg clusters were found. The research paper in Current Biology lists the following highlights from this fossil discovery:

  • Brooded embryos are described in the bivalved arthropod Waptia fieldensis

  • Waptia from the middle Cambrian Burgess Shale had few but large eggs

  • A diversity of clutch and egg sizes evolved during the Cambrian explosion

  • Brooding in primitive arthropods might have required presence of a carapace

The authors explain the significance of the find: "Brood care, including the carrying of eggs or juveniles, is a form of parental care, which, like other parental traits, enhances offspring fitness with variable costs and benefits to the parents." Pointing to another arthropod with smaller eggs from 515 million years ago, they attempt to weave an evolutionary narrative:

The presence of these two different parental strategies suggests a rapid evolution of a variety of modern-type life-history traits, including extended investment in offspring survivorship, soon after the Cambrian emergence of animals. Together with previously described brooded eggs in ostracods from the Upper Ordovician (ca. 450 million years ago), these new findings suggest that the presence of a bivalved carapace played a key role in the early evolution of parental care in arthropods.

The other Cambrian arthropod carried its eggs differently, but no less effectively:

Kunmingella douvillei also presented a different method of carrying its young, as its eggs were found lower on the body and attached to its appendages.

Connecting the dots between small eggs and larger eggs (2mm in Waptia) or where they were carried is the least of the Darwinians' worries. Waptia is a "shrimp-like arthropod" with a lot more body complexity than the ability to lay eggs and hold them under its carapace. It had a nervous system, sensory organs, stalked eyes, antennae, respiration, digestion, and the ability to swim. Nevertheless, the ability to lay eggs and transport them to a protective place constitutes an additional design in this animal, requiring genetics and behavioral preparedness.

It's amusing to see the euphemisms evolutionists use for the Cambrian explosion. The paper spoke of the "Cambrian emergence of animals." The news release calls the Cambrian explosion "a period of rapid evolutionary development when most major animal groups appear in the fossil record." Why call it evolutionary development? If animal groups just "emerged" or "appeared" in the record, that's not evolutionary.

Graham Budd's New "Savannah" Hypothesis

Meanwhile, Graham Budd is back. We saw him in October admitting that the trace fossils at the base of the Cambrian are "bilaterian in origin," not precursors to bilaterians. That notion was strengthened by the news that the "small shelly fossils" may include sclerites from complex animals known as kinorhynchs (see our report). That's not helpful to Darwinians. Now, accompanied by S�ren Jensen, Budd has a new idea to run up the flagpole. In Biological Reviews, he presents "The origin of the animals and a 'Savannah' hypothesis for early bilaterian evolution." The news from the University of Uppsala sets the stage:

The fossil record of animals starts for sure by about 540 million years ago, but their origins before this point have remained obscure. Darwin himself worried about this problem at length in the "Origin of species". But after Darwin was writing, a famous group of fossils were discovered called the Ediacaran biota, named after a remote mine in South Australia where many were found. They are now known to be widespread around the globe from the interval of time just before the animal fossil record starts.

But what are these peculiar organisms? Their very strange morphology has made relating them to modern organisms very difficult, and they have been suggested to be related to anything from plants, fungi and lichens through to recognisable animals such as worms and arthropods.

So what is Budd and Jensen's "savannah" hypothesis? The term is drawn from an evolutionary notion that humans evolved when forests were replaced by grasslands, isolating the forest "hotspots" with distances between them. The change in environment forced our tree-climbing ancestors to come down to the ground so they could travel between the forests, learning to walk upright and forage in the open as they did. A similar situation occurred when the Ediacarans came along, they suggest; scattered nutrient hotspots constituted a "savannah" that created new opportunities for the evolution of motile animals:

In their new 'savannah' hypothesis, they propose that concentration of nutrients both above and below the sediment-water interface were enhanced around the stationary Ediacarans, and the creation of these resource "hot spots" created a very diverse environment, ideal for both diversification and for investment of energy into movement. Rather than the Ediacarans and later animals being direct competitors then, the Ediacarans themselves created a permissive environment that was ideal for higher animals to evolve in. This idea fits well into a modern view of evolution, called "ecosytem engineering" whereby key species (such as beavers) influence the environment in order to create new evolutionary and diversity opportunities for other species. Perhaps then, the Ediacaran taxa weren't impediments but the drivers of the evolution that was eventually to lead to all the rich animal diversity we see today.

Call it the "Come and Get It" theory of the Cambrian explosion. The Ediacarans set the table, put the nutritious food on it, and called out, "Come forth, Animalia!" It's honestly hard not to describe it any other way. The Ediacarans gave their permission? They created opportunities? They became "drivers of the evolution" of animals? The main paper merely states the same ideas with the addition of jargon: "The Ediacaran biota thus played an enabling role in bilaterian evolution similar to that proposed for the Savannah environment for human evolution and bipedality."

It shouldn't be necessary to belabor the point. This hypothesis fails to address the main problem that Stephen Meyer emphasized in Darwin's Doubt: What was the source of the information required to build new complex body plans and integrated organ systems at multiple hierarchical levels? Won't someone please address that question?

Oxygen Again

Let's try two more recent papers. Another paper in Nature Communications looks to oxygen as the cause of animal evolution:

Neoproterozoic (1,000-542 Myr ago) Earth experienced profound environmental change, including 'snowball' glaciations, oxygenation and the appearance of animals....Overall, increased ocean oxidation and atmospheric O2 extended over at least 100 million years, setting the stage for early animal evolution.

The news release from the Birkbeck University of London repeats this theme, implying that oxygen gives permission for animals to evolve: "It took 100 million years for oxygen levels in the oceans and atmosphere to increase to the level that allowed the explosion of animal life on Earth...."

We've already dealt with the just-add-oxygen theory (here and here).

Molecular Clock Again

Last, a dispatch in Current Biology comments on the Yang paper about the molecular clock (see our response here). That paper cast doubt on the precision of molecular clock measurements; here, Pisani and Liu agree:

This imprecision of the molecular clock deep in the history of life is frustrating. While the clock provided hope that divergence times for lineages could be dated in the absence of fossil information, it is now clear that the only way to increase its precision is to improve our knowledge of the fossil record itself, via the discovery of new fossils, resolving the affinities of existing ones, and accurately dating fossil occurrences. With genomic data now available our focus should return to palaeontology, and particularly to the investigation of the early and middle Neoproterozoic. It is evident that in isolation, neither fossils nor molecular data can derive the precise and accurate timescale of life so essential to our efforts to robustly test proposed correlations between the history of life and that of planet Earth.

Obviously this is not helpful to Darwinians either, so it's not surprising that they, too, ignore the information problem.

Waptia fieldensis, via University of Toronto, � Royal Ontario Museum.