The missing fossils argument (Introduction)

by David Turell @, Thursday, January 20, 2022, 15:10 (798 days ago)

Trying to explain gaps in the fossil record by hoping missing fossils will be found is a losing cause with new studies of th e Edicaran and Cambrian gap:

https://reasons.org/explore/blogs/todays-new-reason-to-believe/cambrian-explosion-becom...

"The new phyla that appeared in the Cambrian explosion (a largely marine event) included the first animals to possess skeletons, digestive tracts, circulatory systems, and complex internal and external organs. Not until the Cambrian explosion was there sufficient oxygen in Earth’s atmosphere and oceans for such animals to exist.

"Animals that suddenly appeared at the beginning of the Cambrian period included the most advanced phyla in Earth’s history. We humans belong to the chordate phylum, which is characterized by animals that possess a dorsal hollow nerve cord and a notochord. All vertebrates and many invertebrates belong to the chordate phylum. Paleontologists have discovered fossils of chordates, including some vertebrates, that date back to the very beginning of the Cambrian period.

***

"Two of the best attempts to determine an absolute date for the Cambrian explosion were undertaken by research teams led by Diazhao Chen and Can Chen, respectively. Diazhao Chen and four colleagues obtained uranium-lead zircon ages from the Ediacaran-Cambrian boundary strata, where one stratum contains fossils of Ediacaran (the period prior to the Cambrian) animals and the immediately adjacent stratum contains fossils of Cambrian animals in the Liuchapo Formation in South China.

"The fossil record reveals that the Ediacaran animals were the first to appear on Earth. Unlike the Cambrian animals, the Ediacaran fauna lacked digestive tracts, circulatory systems, skeletons, and complex organs. The record shows that the Ediacaran fauna experienced a sudden worldwide mass extinction event that was quickly followed by the appearance of the Cambrian explosion animals.

***

"They found a composite geological section in southern Namibia of the Ediacaran-Cambrian boundary that provided biostratigraphic and chemostratigraphic data that was bracketed by radiometric dating. Their measurements constrained the date for the Ediacaran-Cambrian boundary to no earlier than 538.99 ± 0.21 million years ago and no later than 538.58 ± 0.19 million years ago. Therefore, they concluded that the faunal transition from Ediacaran to Cambrian biota occurred within less than 410,000 years.

***

"A time window for the Cambrian explosion briefer than 410,000 years is far too brief for any conceivable naturalistic model for the history of life. It would be far too brief even for the appearance of just one new phylum, let alone 30+ phyla. These discoveries make paleontologist Kevin Peterson’s conclusion in his review paper on the Cambrian explosion—published a dozen years ago—all the more compelling: “Elucidating the materialistic basis for the Cambrian explosion has become more elusive, not less, the more we know about the event itself.”8 The same goes for Gregory Wray’s review published in 1992, “The Cambrian ‘explosion’ of body plans is perhaps the single most striking feature of the metazoan fossil record. The rapidity with which phyla and classes appeared during the early Paleozoic coupled with much lower rates of appearance of higher taxa since, poses an outstanding problem for macroevolution.” (my bold)

Comment: I've quoted Bechly in the past: " "The most popular attempt to resolve this discrepancy is the so-called “artifact hypothesis,” which proposes that the Cambrian animal phyla had ancestors, but that those ancestors either left no fossil record or have not yet been found, because of the incompleteness of the fossil record." Now more Bechly: "Recently, I stumbled upon a paper from 2018 that I had previously overlooked, and it proved to be dynamite. It is a study by a research group from the University of Zurich about the transition from the Ediacaran organisms to the Cambrian animal phyla in the Nama Basin of Namibia (Linnemann et al. 2018). What they found is truly mind-blowing. The window of time between the latest appearance date (LAD) of the alien Ediacaran biota and the first appearance date (FAD) of the complex Cambrian biota was only 410,000 years. You read that correctly, just 410 thousand years! This is not an educated guess but based on very precise radiometric U-Pb dating with an error margin of only plus-minus 200 thousand years. This precision is truly a remarkable achievement of modern science considering that we are talking about events 538 million years ago.

So I might add, without fossils, imagining lost fossils disappears. I've left out two supporting study descriptions. The findings are solid.

The missing fossils argument

by David Turell @, Tuesday, May 17, 2022, 21:02 (681 days ago) @ David Turell

New findings in the pre-Cambrian gap period:

https://phys.org/news/2022-05-animals-complex-ecosystems-cambrian-explosion.html

"Early animals formed complex ecological communities more than 550 million years ago, setting the evolutionary stage for the Cambrian explosion, according to a study by Rebecca Eden, Emily Mitchell, and colleagues at the University of Cambridge, UK, publishing May 17th in the open-access journal PLOS Biology.

"The first animals evolved towards the end of the Ediacaran period, around 580 million years ago. However, the fossil record shows that after an initial boom, diversity declined in the run-up to the dramatic burgeoning of biodiversity in the so-called "Cambrian explosion" nearly 40 million years later. Scientists have suggested this drop in diversity is evidence of a mass extinction event roughly 550 million years ago—possibly caused by an environmental catastrophe—but previous research has not investigated the structure of these ancient ecological communities.

"To evaluate the evidence for an Ediacaran mass extinction, researchers analyzed the metacommunity structure of three fossil assemblages that span the last 32 million years of this geological period (between 575 to 543 million years ago). They used published paleoenvironmental data, such as ocean depth and rock characteristics, to look for metacommunity structure indicative of environmental specialization and interactions between species. The analysis revealed increasingly complex community structure in the later fossil assemblages, suggesting that species were becoming more specialized and engaging in more inter-species interactions towards the end of the Ediacaran era, a trend often seen during ecological succession.

"The results point to competitive exclusion, rather than mass extinction, as the cause of the diversity drop in the late Ediacaran period, the authors say. The analysis indicates that the features of ecological and evolutionary dynamics commonly associated with the Cambrian explosion—such as specialization and niche contraction—were established by the first animal communities in the late Ediacaran.

"Mitchell adds, "We found that the factors behind that explosion, namely community complexity and niche adaptation, actually started during the Ediacaran, much earlier than previously thought. The Ediacaran was the fuse that lit the Cambrian explosion.'"

Comment: I have seen the picture of this period in the Edicaran period. They are a variety of frond-like plant-looking, but are thought to be animals. You must download the article to see it:

https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3001289


No complexity like in the Cambrian animals. The phenotypic gap persists, and this article is another Darwinian attempt to shrink the gap.

The missing fossils argument; a new discovery

by David Turell @, Thursday, May 11, 2023, 00:50 (323 days ago) @ David Turell

In a meadow in England:

https://www.scientificamerican.com/article/462-million-year-old-fossil-trove-holds-mini...

"Hidden inside a rocky outcrop near a flock of grazing sheep, a miniature world of marine creatures—whose guts, eyes and even brains remain visible after some 462 million years—has been uncovered by researchers.

"Paleontologists Lucy Muir and Joseph Botting discovered the pint-sized fossil trove within walking distance from their home at Castle Bank Quarry in Central Wales. At the time the aquatic creatures were alive, this area was a rocky sea shelf fringing a volcanic island.

"In a new study published online on May 1 in the journal Nature Ecology and Evolution, the duo and their colleagues in England, Sweden and China describe the site’s ancient inhabitants, most of which are just a couple of millimeters long and include nozzle-mouthed worms, horseshoe crabs, starfish and early barnacles. Also in the fossil trove are tiny enigmatic holdovers from the preceding Cambrian explosion, a period that started about 540 million years ago, when a burst of diverse life-forms emerged.

***

"Over several months the paleontologists discovered the fossils of around 170 different species that likely inhabited the rocky slope along a subsiding volcano. In addition to sponges and worms were trilobites, arthropods sporting grasping appendages and a six-legged animal that looked remarkably similar to a primitive insect that did not appear until millions of years later. There was also an animal reminiscent of Opabinia, a weird wonder of the Cambrian that had five eyes and a trunklike proboscis. Many of these evolutionary oddballs were delicately etched into the ash-colored stone, where soft-body features such as gills, digestive tracts, optic nerves and neural tissue—which rarely fossilize—were easily visible.

***

"...beautifully maintained animals are much rarer in the succeeding Ordovician period. According to Alycia Stigall, a paleontologist at the University of Tennessee at Knoxville, this is potentially because of a change in ocean chemistry during the Ordovician or a rise in burrowing organisms that exposed the remains of other animals to decay. Without these remnants, scientists know little about the majority of soft-bodied organisms that lived in the aftermath of the Cambrian explosion. “Today nonbiomineralizing organisms make up [around] 70 percent of all animals,” she says, referring to soft-bodied creatures. “Snapshots into the history of nonbiomineralizing animals like the Castle Bank fauna is incredibly important for developing a fuller understanding of the history of life,” adds Stigall, who was not involved in the new study.

"The newfound fossils also offer an unparalleled glimpse into a dynamic chapter of evolution called the great Ordovician biodiversification event. “This is when life started to get really interesting,” Muir says. “As animals diversified, ecosystems became a lot more complicated.” While animal sizes stayed constant throughout the Cambrian, some ecosystems seemed to downsize during the Ordovician. Castle Bank’s fossils are generally small. Most of them measure between 1 and 5 mm.

***

"The researchers are still working to describe dozens of Castle Bank fossils in greater detail, including the tube-dwelling tentacled creature and the animal that resembles a possible marine precursor to insects. Like it was during the lockdown, their house is currently overflowing with fossils from the site. “Our spare room is so full, you can't sleep on the bed,” Botting says."

Comment: a great new find. No important gaps closed.

The missing fossils argument; all gaps are real

by David Turell @, Thursday, May 11, 2023, 17:32 (322 days ago) @ David Turell

A review article:

https://evolutionnews.org/2023/05/top-scientific-problems-with-evolution-fossils-2/

"Darwin wrote this about the fossil record in On the Origin of Species:

"By the theory of natural selection all living species have been connected with the parent-species of each genus, by differences not greater than we see between the varieties of the same species at the present day; and these parent-species, now generally extinct, have in their turn been similarly connected with more ancient species; and so on backwards, always converging to the common ancestor of each great class. So that the number of intermediate and transitional links, between all living and extinct species, must have been inconceivably great.

"But the “inconceivably great” numbers of transitional links postulated by Darwin have never been found. Indeed, one of the most prominent features of the fossil record is the Cambrian explosion, in which the major groups of animals (called phyla) appeared around the same geological time in a period called the Cambrian, fully formed and without fossil evidence that they diverged from a common ancestor.

***

"In 1991, a team of paleontologists concluded that the Cambrian explosion “was even more abrupt and extensive than previously envisioned.”

"The abruptness seen in the Cambrian explosion can also be seen on smaller scales throughout the fossil record. Species tend to appear abruptly in the fossil record and then persist unchanged for some period of time (a phenomenon called stasis) before they disappear. In 1972, paleontologists Niles Eldredge and Stephen Jay Gould called this pattern punctuated equilibria. According to Gould, “every paleontologist always knew” that it is the dominant pattern in the fossil record. In other words, the “inconceivably great” numbers of transitional links postulated by Darwin are missing not just in the Cambrian explosion, but throughout the fossil record. (my bold)

"Even if we did have a good fossil record, we would still need our imagination to produce narratives about ancestor-descendant relationships. Here’s why: If you found two human skeletons buried in a field, how could you know whether one was descended from the other? Without identifying marks and written records, or perhaps in some cases DNA, it would be impossible to know. Yet you would be dealing with two skeletons from the same recent, living species. With two different, ancient, extinct species — often far removed from each other in time and space — there would be no way to demonstrate an ancestor-descendant relationship.

"Decades ago, paleontologist Gareth Nelson wrote, “The idea that one can go to the fossil record and expect to empirically recover an ancestor-descendant sequence, be it of species, genera, families, or whatever, has been, and continues to be, a pernicious illusion.” In 1999, evolutionary biologist Henry Gee wrote that “it is effectively impossible to link fossils into chains of cause and effect in any valid way.” He concluded, “To take a line of fossils and claim that they represent a lineage is not a scientific hypothesis that can be tested, but an assertion that carries the same validity as a bedtime story — amusing, perhaps even instructive, but not scientific.'”

Comment: note my bold. Species appear abruptly. Last for some time and disappear. Each abrupt appearance creates a gap. Darwin was wrong in his suppositions. Where does that leave Darwin's common descent. In most cases phenotypic descent can be seen. But abrupt appearance is common. That leads to intelligent design's point. A designer fits this pattern. He can stick in a new design wherever He wishes.

The missing fossils argument; the Devonian explosion

by David Turell @, Friday, May 12, 2023, 19:00 (321 days ago) @ David Turell

Another huge gap refuting Darwinian gradualism:

https://evolutionnews.org/2023/05/fossil-friday-the-devonian-nekton-revolution/


"Klug et al. (2010) described a previously overlooked radical change in the composition of the marine fauna of the Early Devonian, which they called the Devonian Nekton Revolution. Prior to this abrupt event, the marine ecosystems were dominated by organisms that lived either close to the seafloor (demersal) or passively drifting as plankton. Between 410-400 million years ago, a very sudden and enormous expansion of actively swimming (nektonic) animals occurred in the Devonian era, when groups such as ammonoid cephalopods and jawed fish made their first appearance. Within just 10 million years such active swimmers increased from only 5 percent to about 75 percent of the marine faunal biodiversity (see the chart below).


"The authors commented in a later paper that “this macroecological event corresponds to an explosive trend from planktonic and demersal marine animals toward true nekton as represented by the great diversification of jawed fish and ammonoids, reflecting a selection for swimming capabilities. It coincided with macroevolutionary transformations among various mollusc groups” (Monnet et al. 2011) and “is strongly linked with the rise of predatory jawed vertebrates, which also became more active swimmers in the same interval” (Klug et al. 2017, also see Anderson et al. 2011)".

Comment: as fully note before, species suddenly appear, last a while and then disappear. Nothing like Darwin theory of gradualism.

The missing fossils argument: Cambrian jellyfish

by David Turell @, Wednesday, August 02, 2023, 14:54 (239 days ago) @ David Turell

Just found:

https://www.sciencealert.com/spectacularly-preserved-jellyfish-found-in-500-million-yea...

"Something truly and wonderfully special has been found in a 505-million-year-old Canadian fossil bed.

"There, preserved in the especially fine silt of a lagerstätte, paleontologists found more than 170 exquisite fossils of ancient jellyfish that swam Earth's waters hundreds of millions of years before the first dinosaurs trod its soil.

"The find is incredible because soft tissues are so rarely preserved in the fossil record, and these are so beautifully immortalized that even anatomical details, like their little jelly tentacles, are visible. And the newly discovered species, Burgessomedusa phasmiformis, now represents the earliest known jellyfish on the planet.

"'Although jellyfish and their relatives are thought to be one of the earliest animal groups to have evolved, they have been remarkably hard to pin down in the Cambrian fossil record," says paleontologist Joe Moysiuk of the University of Toronto and Royal Ontario Museum in Canada.

"'This discovery leaves no doubt they were swimming about at that time."

***

"Jellyfish, belonging to the phylum Cnidaria, are very soft tissue, so we don't expect them to be preserved all that often, if at all. Cnidarian preservation is not unknown, though. Cnidarians of the polyp variety – those that are anchored to rocks – have been found in fossil beds dating up to 560 million years ago.

"Polyps are the early life stage of modern jellies, but there are some polyps that remain polyps. Scientists believe that, evolutionarily, polyps came first and later transitioned into free-swimming creatures – Cnidarians of the medusa variety, otherwise known as jellyfish.

***

"The discovery of Burgessomedusa gives us a new baseline for calculating the timeline of jellyfish evolution. And it drives home the diversity of Cambrian marine ecosystems, which have the appearance of domination by hard-shelled creatures, as those are more readily preserved as fossils. Instead, they would have been rich and complex, with a range of squishy predators, too.

"'Finding such incredibly delicate animals preserved in rock layers on top of these mountains is such a wondrous discovery," says paleontologist Jean-Bernard Caron of the Royal Ontario Museum.

"'Burgessomedusa adds to the complexity of Cambrian food webs, and like Anomalocaris, which lived in the same environment, these jellyfish were efficient swimming predators. This adds yet another remarkable lineage of animals that the Burgess Shale has preserved, chronicling the evolution of life on Earth.'"

Comment: the Cambrian had its own ecosystem. A new discovery but the gap remains.

The missing fossils argument; all gaps are real

by David Turell @, Tuesday, August 29, 2023, 14:46 (212 days ago) @ David Turell

New discoveries in a known Cambrian animal:

https://www.cell.com/current-biology/fulltext/S0960-9822(23)01065-5?dgcid=raven_jbs_aip...

"Highlights:

"CT imaging clarifies head structure in the Cambrian stem-group euarthropod Kylinxia

"Kylinxia has three eyes and four pairs of biramous head limbs

"The six-segmented head of living arthropods dates to shared ancestry with Kylinixia

"Phylogeny supports homology of frontal appendages across stem-group arthropods (my bold)

"The early Cambrian Kylinxia zhangi occupies a pivotal position in arthropod evolution, branching from the euarthropod stem lineage between radiodonts (Anomalocaris and relatives) and “great-appendage” arthropods. Its combination of appendage and exoskeletal features is viewed as uniquely bridging the morphologies of so-called “lower” and “upper” stem-group euarthropods. Microtomographic study of new specimens of Kylinxia refines and corrects previous interpretation of head structures in this species. Phylogenetic analyses incorporating new data reinforce the placement of Kylinxia in the euarthropod stem group but support new hypotheses of head evolution. The head of Kylinxia is composed of six segments, as in extant mandibulates, e.g., insects. In Kylinxia, these are an anterior sclerite associated with an unpaired median eye and paired lateral eyes (thus three rather than five eyes as was previously described ), deutocerebral frontal-most appendages, and four pairs of biramous appendages (rather than two pairs of uniramous appendages). Phylogenetic trees suggest that a six-segmented head in the euarthropod crown group was already acquired by a common ancestor with Kylinxia. The segmental alignment and homology of spinose frontal-most appendages between radiodonts and upper stem-group euarthropods is bolstered by morphological similarities and inferred phylogenetic continuity between Kylinxia and other stem-group euarthropods."[/b] (my bold)

Comment: An early stem group is further described with three eyes. Such complexity with no precursors is typical of the Cambrian Explosion.

The missing fossils argument; all gaps are real

by David Turell @, Saturday, September 23, 2023, 18:40 (187 days ago) @ David Turell

First jellyfish in th2 Cambrian:

https://evolutionnews.org/2023/09/fossil-friday-jellyfish-body-plan-and-life-cycle-orig...

"The Cambrian Explosion certainly represents the best-known example of abrupt appearances in the history of life. Most of the body plans of bilaterian animal phyla appeared on the scene without known precursors that would document the incremental and gradual evolution predicted by the modern neo-Darwinian paradigm. However, the abrupt appearances in the Cambrian Explosion are not restricted to bilaterian animals. In a previous article I meticulously elaborated that unequivocal sponges also first show up in the Lower Cambrian (Bechly 2020), and Precambrian evidence for cnidarians is at least controversial (Bechly 2022).

"Now a new study by Moon et al. (2023) suggests that the distinctive medusoid body plan of jellyfish and their complex life cycle with sessile polyp stage and free-swimming medusa stage also originated during the Cambrian Explosion (News Staff 2023), adding to the enormous biological importance of this crucial event. The scientists examined 182 exceptionally well-preserved fossil jellyfish from the Lower Cambrian of the famous Burgess Shale in the Canadian Rocky Mountains, which is quite remarkable considering that jellyfish are roughly 95 percent water and therefore not the most likely candidates for well-preserved fossils. The animals were named Burgessomedusa phasmiformis and had a cuboidal umbrella of up to 8 inch size with over 90 very short and finger-like tentacles.

'Remarkably, these animals can already be placed within the crown group of the living cnidarian clade Medusozoa, which is not exactly what Darwinists should expect to find as the very first and oldest fossil record of a group. The new study also clarifies that “previously described macrofossils, putatively representing medusa stages of crown-group medusozoans from the Cambrian of Utah and South China, are here reinterpreted as ctenophore-grade organisms.” This shows that such identifications should always be taken with a grain of salt.

Comment: Darwin's expectation that intermediate forms would be found has not happened during the 170+ years that followed. All the gaps are real.

The missing fossils argument; gaps everywhere

by David Turell @, Saturday, November 18, 2023, 19:46 (131 days ago) @ David Turell

From evolution news:

https://evolutionnews.org/2023/11/fossil-friday-protists-add-to-the-cambrian-explosion/

"When talking about the Cambrian Explosion, the focus is usually on the abrupt appearance of bilaterian animal phyla with their distinct body plans, which has been called a Big Bang of life. However, the Cambrian Explosion is not restricted to these animals. As I have shown in previous articles, non-bilaterian animals like true sponges and jellyfish also first appeared in the Lower Cambrian. Today we will have a look at a largely ignored part of the Cambrian Explosion. That is the abrupt appearance of several major groups of protists.

"Radiolarians represent an important group of marine zooplankton with beautiful siliceous mineral skeletons that were famously featured in wonderful drawings by the German pioneer Darwinist Ernst Haeckel. Their oldest fossil record is from the Earliest Cambrian (Ediacaran-Cambrian boundary) to Middle Cambrian of China. Thus, they appear right together with the Cambrian Explosion of animal phyla.

"Foraminiferans are amoeboid marine protists, which mostly live in the seafloor sediment and have a calcium carbonate skeleton. Their oldest uncontroversial fossil record is again from the Early Cambrian. Pawlowski et al. (2003) therefore concluded that “Fossil Foraminifera appear in the Early Cambrian, at about the same time as the first skeletonized metazoans.” More recent evidence for late Ediacaran foraminiferans suggests that this group may have originated already with the Avalon Explosion rather than the Cambrian Explosion, but even Hua et al. (2010) admitted that “the oldest unambiguous foraminifers are from Early Cambrian Atdabanian Stage strata.” Possible testate amoebae and possible foraminiferans (Rhizaria) have even been reported from 716-635 million-year-old carbonate rocks in Namibia and Mongolia, which date to a time right after the Sturtian glaciation of the Cryogenian “Snowball Earth”. However, these determinations are only tentative and far from established. At least the tintinnid determinations in the same work have been strongly disputed by Lipps et al. (2012).

***

"Other groups of protists appeared at other periods in Earth history, but they also originated abruptly without gradual transition from assumed precursors. For example, diatoms suddenly appear in the fossil record of the Early Jurassic about 182 million years ago. Coccolithophores (Hapotophyta), which form the chalk of the famous White Cliffs of Dover, appear at the Norian-Rhaetian boundary about 208.5 million years ago.

***

" Darwin’s dilemma of the lack of fossils for this ancient age therefore still holds for at least the ciliates. If there are tintinnid fossils from this ancient time, they have yet to be discovered.”

"Not even the tiniest and most abundant organisms seem to confirm the gradualist predictions of Darwinian evolution. Whenever empirical data from the actual fossil record are used to test this crucial part of the theory, it simply fails. Since gradualism is strongly refuted by the evidence, the theory must be false, because even Richard Dawkins, arguably the most ardent modern popularizer of Darwinism, clearly stated in his bestselling book The Greatest Show on Earth (Dawkins 2009) that “evolution not only is a gradual process as a matter of fact; it has to be gradual if it is to do any explanatory work.” Clinging to a refuted paradigm, in spite of the accumulated conflicting evidence, is not science but rather irrational dogmatic belief." (my bold)

Comment: this is Gould's vindication of his statement gaps are everywhere. I hope this removes dhw's irrational clinging to stepwise evolution as a dogmatic belief. Gaps mean new organism require design because new irreducible complexity is required.

The missing fossils argument; Bechly on finding ancestors

by David Turell @, Monday, March 11, 2024, 21:47 (17 days ago) @ David Turell

A hard task:

https://evolutionnews.org/2024/03/fossil-friday-direct-fossil-ancestors-of-living-species/

"It is the often posed obvious question of whether there are any known fossil species that are believed to be the direct ancestors of living species, thus not just cousins on side branches of the stem group but actual stem species on the stem lineage.

"Given that there are millions of living species and each of them must have had numerous successive ancestral species in their stem lineage, we might expect to find a lot of examples in the technical literature. However, actually there are only very few cases, where such direct ancestor-descendant relationships have been proposed. All these cases are only weakly supported and not uncontroversial. They are generally restricted to groups with a rich Plio-Pleistocene fossil record.

"Among the few examples for mammalian species would be the extinct European canids Canis etruscus and Canis mosbachensis as assumed ancestors of modern wolves, or the extinct Bison antiquus and Bison occidentalis as assumed ancestors of the modern American bison, or the extinct Elephas hysudricus as ancestor of the modern Asian elephant . Another example might be the steppe mammoth Mammuthus trogontherii as ancestor of the woolly mammoth Mammuthus primigenius, which only went extinct about 4,000 years ago on Wrangel Island and thus may count as modern species. Some paleoanthropologists suggested that the Eurasian archaic human Homo heidelbergensis was via Homo steinheimensis the direct ancestor of Neanderthals, and the African archaic human Homo rhodesiensis could be the direct ancestor of later Homo sapiens in north-eastern Africa, but this is quite controversial, as is the valid taxonomic status of these fossil human species themselves.

"More examples for assumed direct ancestors of living species are found in Pliocene and Pleistocene marine protists among the foraminiferans and radiolarians, mainly because we have a long-lasting undisturbed microfossil record of these unicellular organisms in deep sea sediments. But of course, this raises the fuzzy question of chronospecies and whether we are only seeing microevolution within a species rather than speciation (which arguably could be an arbitrary distinction).

"Overall, it looks like the evidence for direct fossil ancestors is extremely slim to say the least. Why is that? Of course, one possibility would be that common descent is wrong, but even young earth creationists affirm that speciation does occur and that wolves or bisons had ancestral species respectively. So, could there be another explanation?

Indeed, there are two general problems concerning the recognition of direct ancestors in the fossil record:

"1.) Even though the fossil record is pretty complete on the macroevolutionary level of higher taxa (family and above), the fossil record will always be highly incomplete on the lower taxonomic levels because it was estimated that less than 1% of all species were preserved as fossils (not to speak of having been discovered). This seems to make it very unlikely to find exactly the direct ancestor of a particular living species. However, renowned expert Mike Foote (1996) estimated the probability of ancestors in the fossil record and found the probability to find ancestor-descendant pairs not negligible and likely underestimated.

"2.) There is a general methodological impossibility to diagnose a direct ancestor species based on morphological characters, because all of its primitive characters are shared with other stem group representatives and outgroup taxa, while all of its derived characters are inherited by its descendant species. There is no diagnostic character that would label an ancestor as such. We should expect an ancestor to lack any autapomorphies that would indicate its position on a side branch, but given the incomplete preservation of fossils we can never know if such characters were just not preserved or even have not been preservable at all (e.g., soft tissue, genetic, behavioral, physiological characters). The only theoretical case where a stem species could possess a unique diagnostic character, would be the esoteric case when it developed a derived trait that then immediately got lost in the descendent species. However I don’t know of a single example, and such a case would also not be empirically distinguishable from a side branch autapomorphy. So overall, fossil ancestors can in principle not be recognized as such based on their characters. Therefore, there can always only be plausibility arguments, based on a continuous preservation and certain criteria such as occurrence older but in the same region as the descendant species. (my bold)

"...Therefore, modern paleobiologists generally do not even look for ancestor-descendant relationships but only for sister group relationships in terms of more recent common descent.

"So, even if Darwinism were true, we would not expect to find a lot of direct fossil ancestors of living species. But on the other hand, there is certainly no positive support for Darwinism from such elusive ancestors either. I would consider this to be a draw." (my bold)

Comment: I would remind the reader Bechly also points out the very high completeness rate of the fossil record and many more small new findings may appear, but the present gaps are real and not likely to be erased.

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