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2.9: Cambrian Period (540-485 million years) - Geosciences

2.9: Cambrian Period (540-485 million years) - Geosciences


Highlights of the Early Paleozoic Era

Evolution of early plant and animal life (dominated mostly marine invertebrates) is revealed in the fossil record of the early part Paleozoic Era. Primitive land plants, insects, and the first vertebrates also appear.

Cambrian Period (540-485 million years)

The Cambrian Period is the oldest of the named geological periods of the Paleozoic Era. At the beginning of the Cambrian Period the combination of tectonic forces and erosion of the landscape allowed shallow seas to gradually cover much of North America. Shallow seas covered most of what is now the Great Basin, Rocky Mountains, and Great Plains in the west, and much of East Coast, Appalachian region, and most of the Midwest. The shallow seas withdrew at the end of Cambrian time, but what was left behind was a blanket of Cambrian sedimentary rocks, collectively called the Sauk Sequence (see Figures 2-20 and 2-21, also see Figure 2.13). The base of the Sauk Sequence rests on an eroded surface of ancient Precambrian-age (mostly metamorphic and igneous rocks of the core of more ancient mountain systems). This sequence boundary is called the Great Unconformity. The Great Unconformity is exposed in many places throughout the western United States, and is particularly well known from exposures along the base sedimentary rocks of Cambrian age exposed in the Grand Canyon within the canyons Inner Gorge (see Figure 2.14). The Great Unconformity can be traced across most of North America wherever the base of the Cambrian-age Sauk Sequence is exposed.

Calcareous skeletal shell remains first appear in the Cambrian Period.

The term Cambrian explosion refers to evidence in the fossil record which shows that all major phyla were established in the transition from latest Precambrian to the Early Cambrian Period (about 700 to 541 million years ago) (Figure 2.22). The cause of this radiation from earlier metazoan life forms is uncertain, but it may have been driven by global climate changes (hot to cold cycles) and the establishment of unique habitats (niches) which allowed species to evolve separately from common ancestors. In Cambrian time, escalation of predator-prey relationships and increased competition appears to have driven rapid evolution of new species (along with extinctions). In Cambrian time, shelled organisms first appear in abundance in sedimentary deposits preserved from that time period. The fossil record from Cambrian time show that organisms with chitonous and calcareous shells and exoskeletons appeared and diversified. Many Cambrian-age organisms have eyes, legs (or pods), spinal chord-like features, segmented body plans, and other unique body parts and characteristics. Representatives of all phyla from the Cambrian Explosion still exist in the world today (Figure 2.22). Sedimentary rocks from Cambrian Period are typically rich in evidence of life activity. They preserve an abundance of bioturbation features (also called trace fossils) even if the life forms that created them are not preserved (an example of bioturbation is shown in Figure 2.23).

Invertebrates dominate the fossil record in the early Paleozoic Era. An invertebrate is an animal lacking a backbone (spinal column or spinal chord), such as an arthropod, mollusk, annelid worm, coelenterate, echinoderm, and many others. The classification of invertebrates constitute a division of the animal kingdom, comprising about 95 percent of all animal species and about 30 different known phyla.

By the end of the Cambrian Period several groups of invertebrates were well established in shallow marine environments, perhaps most notably were trilobites, brachiopods, crinoids, bryozoans, sponges, and gastropods (snails) are locally common fossils preserved in Cambrian sedimentary rocks (Figures 2-24 and 2-25). At the end of the Cambrian Period, sea level fell and a long period of exposure and erosion occurred throughout North America and the other continents worldwide.


Rare fossilized embryos more than 500 million years old found

The Cambrian Period is a time when most phyla of marine invertebrates first appeared in the fossil record. Also dubbed the "Cambrian explosion," fossilized records from this time provide glimpses into evolutionary biology when the world's ecosystems rapidly changed and diversified. Most fossils show the organisms' skeletal structure, which may or may not give researchers accurate pictures of these prehistoric organisms. Now, researchers at the University of Missouri have found rare, fossilized embryos they believe were undiscovered previously. Their methods of study may help with future interpretation of evolutionary history.

"Before the Ediacaran and Cambrian Periods, organisms were unicellular and simple," said James Schiffbauer, assistant professor of geological sciences in the MU College of Arts and Science. "The Cambrian Period, which occurred between 540 million and 485 million years ago, ushered in the advent of shells. Over time, shells and exoskeletons can be fossilized, giving scientists clues into how organisms existed millions of years ago. This adaptation provided protection and structural integrity for organisms. My work focuses on those harder-to-find, soft-tissue organisms that weren't preserved quite as easily and aren't quite as plentiful."

Schiffbauer and his team, including Jesse Broce, a Huggins Scholar doctoral student in the Department of Geological Sciences at MU, now are studying fossilized embryos in rocks that provide rare opportunities to study the origins and developmental biology of early animals during the Cambrian explosion.

Broce collected fossils from the lower Cambrian Shuijingtuo Formation in the Hubei Province of South China and analyzed samples to determine the chemical makeup of the rocks. Soft tissue fossils have different chemical patterns than harder, skeletal remains, helping researchers identify the processes that contributed to their preservation. It is important to understand how the fossils were preserved, because their chemical makeups can also offer clues about the nature of the organisms' original tissues, Schiffbauer said.

"Something obviously went wrong in these fossils," Schiffbauer said. "Our Earth has a pretty good way of cleaning up after things die. Here, the cells' self-destructive mechanisms didn't happen, and these soft tissues could be preserved. While studying the fossils we collected, we found over 140 spherically shaped fossils, some of which include features that are reminiscent of division stage embryos, essentially frozen in time."

The fossilized embryos the researchers found were significantly smaller than other fossil embryos from the same time period, suggesting they represent a yet undescribed organism. Additional research will focus on identifying the parents of these embryos, and their evolutionary position.

Schiffbauer and his colleagues published this and related research in a volume of the Journal of Paleontology which he co-edited.


Scientists Discover 500 Million-Year-Old Fossilized Embryos

For about the first 3.4 billion years that life existed on Earth, creatures were very simple and their evolution was fairly slow. Then an 80-million-year timespan came along that sparked countless new marine species, many of which became increasingly complex. The rapid expansion of biodiversity is reflected in the name of the time period: the Cambrian explosion. Over 140 fossilized embryos of soft-bodied marine creatures from this time period were discovered by a team of researchers led by James Schiffbauer from the University of Missouri. Analyzing the fossils could provide a wealth of information about the anatomy of these early complex organisms. The team published two papers on the topic which will appear in a special issue of the Journal of Paleontology

Fossilization is a difficult process, but hard tissues have a considerably advantage. Soft tissue is much more difficult to preserve, because the decomposition rate is much faster. For this reason, there isn’t a lot of of fossils of the earliest soft-bodied animals and not much is known of their anatomy. “The Cambrian Period, which occurred between 540 million and 485 million years ago, ushered in the advent of shells,” Schiffbauer explained in a press release. “Over time, shells and exoskeletons can be fossilized, giving scientists clues into how organisms existed millions of years ago. This adaptation provided protection and structural integrity for organisms. My work focuses on those harder-to-find, soft-tissue organisms that weren’t preserved quite as easily and aren’t quite as plentiful.”

The spherical fossils were retrieved from the lower Cambrian Shuijingtuo formation in South China. Because there are different chemical processes at play when soft tissue is preserved versus hard tissue, the researchers now have a unique opportunity to investigate the animal’s body plan.

“Something obviously went wrong in these fossils,” Schiffbauer. “Our Earth has a pretty good way of cleaning up after things die. Here, the cells’ self-destructive mechanisms didn’t happen, and these soft tissues could be preserved. While studying the fossils we collected, we found over 140 spherically shaped fossils, some of which include features that are reminiscent of division stage embryos, essentially frozen in time.”

Although fossilized embryos from that time period have been discovered before, these are much smaller and could possibly represent a yet-unidentified species. The team is currently analyzing these fossils and hopes to have conclusive results to announce in the future not only of their identity, but also of their evolutionary position in the grand scheme of life.

Deep-water Ediacaran fossils from the Mackenzie Mountains, NW Canada (Narbonne et al.). 1, Hiemalora (left) and Aspidella (right) 2, Namalia Germs, 1968 3, Primocandelabrum Hofmann, O𠆛rien and King, 2008 with Aspidella-like holdfasts, several of which exhibit stems or fronds (arrows) 4, close-up of Primocandelabrum showing an Aspidella-like disc at its base and candelabra-like branches at the distal end of the preserved frond (arrows). Scale bars represent 1 cm or 1 cm increments.


Tardigrades – indestructible animals

These “bears” invisible to the naked eye are one of the most extraordinary animals on Earth. Their survival skills and appearance amaze and also make you wonder. Probably, because of these two features, they are seen as extraterrestrial creatures… Let’s take a look at the cosmic tardigrades.

Classification

  • Kingdom: Animalia
  • Superphylum: Ecdysozoa
  • Phylum: Tardigrades
  • Classes:
    • Heterotardigrada
    • Eutardigrada
    • Mesotardigrada

    Evolution

    The first fossils resembling tardigrades were found in Siberia. This finding dates back to the Cambrian period (about 540-485 million years ago).

    On the basis of genetic studies, two theories have emerged. The first one says that tardigrades are the closest relatives of arthropods and Onychophora, and the second one says that they are closer to the nematodes. However, the latter one has been rejected after conducting additional DNA analyses.

    The latest conclusions have shown that tardigrades are the sister group of Lobopodia, which includes the abovementioned Onychophora.

    Tardigrades (Tardigrada).

    Occurrence – from one extremity to another

    Tardigrades are cosmopolitan animals – they can be found in every region of the world, unless we don’t have a microscope :). Some species inhabit terrestrial, damp mosses, lichens, forest litter and soil, and some prefer freshwater or marine environment. In the course of evolution, plenty of species of tardigrades have developed, and each of them is adapted to a different habitat.

    These animals that are invisible to the naked eye can survive in various conditions. They have been found in hot springs and on top of the Himalayas, under thick layers of ice, and in ocean sediments. Many of species chose ponds, lakes, or meadows for their habitats, and other live in stone walls.

    The common denominator of all tardigrades is moisture, although, they can do without it even for… 100 years! Besides, it’s not their only skill that is amazing.

    Tardigrades (Tardigrada).

    Anatomy

    The elongated body is supported by 3-4 pairs of thick legs. Usually, the body length is between 0.3 and 0.5 mm (0.011-0.019 in), but some species can be about 1.2 mm (0.047 in) long.

    Appearance

    The body is clearly segmented into a head, trunk, and abdomen. The middle part, consisting of three segments, is equipped with legs without joints, but the microscopic feet have 4-8 claws. The cuticle consists of chitin and protein.

    Tardigrades, similarly to crustaceans and insects, which they are the most closely related to, moult regularly.

    Tardigrades (Tardigrada).

    Circulatory system

    The body cavities consist of the circulatory system, but the only place where it can be found is around the gonad.

    They don’t breathe…

    Tardigrades have no airways, so there is no gas exchange. Some species possess tubular glands placed around the rectum, that may serve as excretory organs. They resemble the Malphigian tubules, characteristic for arthropods. However, the role of this organ in tardigrades has not been fully known.

    Tardigrades (Tardigrada).

    Food and defecation

    The tubular mouth on the head has teeth-like structures, thanks to which the animal pierces the plant cells, algae, or small invertebrates, to suck out their contents. The food goes from the mouth through the pharynx to a short esophagus which is connected to the intestines that constitute the most of the body length. Redundant metabolic products are excreted on an ongoing basis, or only during moulting (feces are detached from the body with the dead cuticle). The way of defecation is closely related to the species.

    Brain

    The brain consists of several groups of neurons. This organ is connected with a large ganglion, which is located below the esophagus. A double ventral nerve cord runs the length of the body from there. It is responsible for leg movements, that are connected with it with special nerve fibers.

    Sight

    Many species possess a pair of ommatidia – conical organs (elements of the compound eyes) responsible for vision. Apart from the eyes, tardigrades have sensory bristles that cover the head and trunk.

    Tardigrades (Tardigrada).

    Reproduction

    Many tardigrades reproduce by parthenogenesis (the development of the young from an egg cell without a spermatozoon), but gonochorism also occurs. Females have a cloaca, and males two separate openings in the back of the body.

    Tardigrades are egg-bearing, and fertilization is external. Mating occurs during moulting, when the female shows egg cells along with the redundant cuticle layer. After moulting, the male covers the egg cells with sperm.

    However, external fertilization does not always occur, because there are species that have internal fertilization, and it also occurs when the female moults. After about 14 days after fertilization, the eggs hatch.

    As tardigrades are eutelic (they have the same number of body cells since birth), their growth is based not on cell multiplication, but on the enlargement of particular, already existing cells.

    Tardigrades (Tardigrada).

    Survival skills

    Tardigrades can survive in conditions that would kill every other organism. Although it sounds incredible, these animals endure extremes that are lethal for humans, including:


    Yoho National Park

    Yoho National Park is a protected area located in the Rocky Mountains, in the southeast corner of British Columbia. The park was established in 1886, initially as the Mount Stephen reserve, making it (along with Glacier National Park, established the same day) the second oldest national park in Canada, following Banff. Spanning 1,313 km,2 the park features 28 mountain peaks above 3,000 metres. Yoho National Park is one of seven parks in the Rocky Mountains that make up the Canadian Rocky Mountains UNESCO World Heritage site (the others are Jasper, Banff and Kootenay national parks, and Mount Robson, Mount Assiniboine and Hamber provincial parks). Among the reasons for the UNESCO designation are the Burgess Shale sites, several of which are located in Yoho National Park, featuring fossils from 540 million years ago. The name Yoho comes from a Cree expression of awe and wonder.

    Yoho National Park is located in the Rocky Mountains, in the southeast corner of British Columbia.

    Location

    Yoho National Park is in the Rocky Mountains in southeastern British Columbia. It shares its eastern border with Banff National Park, part of its southern border with Kootenay National Park, and part of its western boundary with Hamber Provincial Park. The town of Field is located within the park’s boundaries outside the park Golden, BC and Banff, Alberta are the closest towns.

    Geology

    During the Precambrian age, 1 billion years ago, the mountains that make up Yoho National Park did not exist. The entire Rocky Mountain System, stretching from the Gulf of Mexico to the Arctic Ocean, was flat. Gradually, this area began to sink below sea level and fill with sea water. Over millions of years, sediments such as mud, silt and sand were deposited into this inland sea from nearby rivers. As more and more sediment was added, the bottom of the sea continued to sink, creating layers of sediment thousands of metres deep.

    About 75 million years ago, forces within the Earth pushed the sediment above sea level, compressing the rocks so that they folded, buckled and broke, forming the Rocky Mountain System. Erosion, from forces such as rain, running water and glaciers, continued to shape the mountains into their current formations.

    Burgess Shale

    Burgess Shale is an area of layered rock featuring fossils from the Cambrian period (540 – 485 million years ago). In Canada, sites featuring Burgess Shale fossils are found in Yoho and Kootenay national parks. The fossils in Burgess Shale capture the end of the Cambrian Explosion, when, over millions of years, most major animal groups appeared in the fossil record. While there are sites around the world that feature fossils from the Cambrian period, these sites mainly include hard-bodied organisms such as shellfish. By comparison, Burgess Shale is primarily made-up of rarely preserved soft-bodied organisms, providing scientists with the world’s clearest record of Cambrian marine life.

    These organisms lived in the sea that once covered the location of the Rocky Mountains. Sediment flowing into the sea buried both dead and living animals. As more and more sediment accumulated, the organisms were compressed and fossilized. As this process was repeated the layers of fossils now found in the Burgess Shale were created.

    Flora and Fauna

    Yoho National Park is home to many alpine and subalpine plants. Several species of coniferous trees are common: whitebark and lodgepole pine, white and Engelmann spruce, and Douglas and subalpine fir. Shrubs include white rhododendron, dwarf birch and alpine bearberry. Wildflowers, such as anemones, lilies and violets, bloom in the park’s lower regions.

    The park is also home to white-tailed and mule deer, moose, and wapiti. Mountain goats roam the higher altitudes, and carnivorous animals include grizzly bears, wolverines and coyotes. Birdlife is varied, and includes the golden eagle, white-tailed ptarmigan and the gray jay. High altitude streams often contain too much silt to be habitable for fish however streams and rivers in the lower valley include trout as well as whitefish and some northern pikeminnow. Some lakes are home to a variety of trout, including bull, lake, speckled, and cutthroat.

    Indigenous Peoples

    Yoho National Park was used primarily by the Ktunaxa (Kootenay) as a seasonal route to the plains on the eastern side of the Rocky Mountains. While other routes existed to the south of the park, these southern passages put the Ktunaxa in contact with the Siksikaitsitapi (Blackfoot Confederacy), with whom they were not friendly. Instead, the Ktunaxa likely used Kicking Horse Pass to access the plains, where they hunted bison on the territory of their allies, the Cree and the Stoney-Nakoda, and traded ochre with them.

    While historians assert that Indigenous people were forcibly removed or barred from most national parks in Canada, there is little detail about what such an exclusion from Yoho National Park may have looked like. By comparison, much has been written about the removal of Indigenous people from neighbouring Banff National Park. In Banff, tensions centred primarily on the Stoney-Nakoda’s use of the park as a hunting ground. While Banff is made up of both valleys and mountains, Yoho is predominantly high peaks, making it less desirable for hunting. For this reason, most conflict over hunting rights likely played out in Banff as opposed to Yoho National Park.

    In addition, by 1888 — two years after the creation of Yoho — plains bison had all but disappeared from Canada, meaning that the Ktunaxa’s seasonal trips through the park were likely less frequent.

    Creation of Yoho National Park

    In 1858, James Hector, a Scottish geologist travelling with the Palliser Expedition, became the first European to encounter Kicking Horse Pass. It’s said Hector’s horse kicked him in the chest at this juncture, hence the name of the pass. Later, the Canadian Pacific Railway used the corridor to connect British Columbia to the rest of the country. A hotel and restaurant were built at the base of Mount Stephen so that the CPR’s heavy dining cars didn’t have to travel up the mountain. The restaurants were the beginning of the Mount Stephen reserve, which was renamed Yoho Park Reserve in 1901.

    Internment Camp

    Otter internment camp, Yoho National Park, British Columbia, 1916.

    During the First World War, the federal government interned 8,579 Canadians and recent immigrants as prisoners of war in camps across the country. Known as “enemy aliens,” they originated from the countries Canada was at war with, namely Germany, Austria-Hungary, Turkey and Bulgaria. Four of these camps were set up in national parks: Banff, Jasper, Mount Revelstoke and Yoho. The camp at Yoho National Park was known as Camp Otter. It was located about 13 km southwest of Field, BC and operated from 6 September 1915 to 23 October 1916.

    The prisoners of war were used as cheap labour during a time when the parks system was receiving little government funding. At Camp Otter the men built a new highway and a bridge to the Kicking Horse River. At one point, some prisoners tried to escape via a tunnel from the cafeteria to the bush, built using a shovel and cutlery. Their plan was discovered before any getaway was attempted.

    Facilities and Activities

    Visitors to Yoho National Park can camp, hike, mountain climb, ski, mountain bike and snowshoe. They also may visit the park’s three national historic sites, Abbot Pass Refuge Cabin, Kicking Horse Pass and Twin Falls Tea House, or they can take a guided tour of the Burgess Shale.


    The Collapse of Darwinism and the Fact of Creation

    The premise of this Harun Yahya group video is that evolution has been disproven based on science. The hour-long video is broken into three parts: 1) The Origin of Life (mins 0:35-20:30), 2) Imaginary Mechanisms of Evolution (mins 20:30-34:00 ), and 3) The Fossil Record (mins 34:00-60:10). The presentation does not provide a balanced discussion, but rather makes blanket statements in order to create the impression that scholars no longer support natural selection (biological evolution) as the dominant paradigm to explain the diversity of life on Earth. The video uses an abundance of stock images of animals and “scientists” (people in lab coats and looking into microscopes).

    Summary:

    Part 1 . The video opens by noting the position of Earth within the larger universe, that is, it’s one planet orbiting one of the universe’s 300 billion stars. The “design” and “harmony” of the planet and the life on it is emphasized. While introducing Darwin, the video suggests that Darwin’s theories denied the existence of God. It then summarizes some research done in the mid twentieth century to determine the origins of life (abiogenesis). The discussion continues with the “complexity” of the cell, and the “impossibility” of complex organisms arising through “coincidence”. The first section closes with a discussion of DNA and the information it contains. Part 2: selection, which it defines as “the idea that strong individuals that are well adapted will survive”. It summarizes the work of Jean-Baptiste Lamarck (d. 1829), who developed a prior theory about evolutionary change. The video suggests that both Lamarck’s and Darwin’s theories are “contrary to some fundamental laws of biology” (23:50). Darwin is quoted with concerns over “any complex organ” that could not have been formed over numerous modifications. The development of genetics in the twentieth century is summarized, stating that “efforts by evolutionists in the twentieth century do nothing but confirm that natural selection has no evolutionary power.” (26:00) The concept of irreducible complexity is introduced to explain what the video suggests Darwin’s theory could not. Mutation as a mechanism for the change in DNA is presented, but the video states that mutations only harm living beings (28:20) Richard Dawkins is presented as being unable to produce an example (30:00). The section closes with a quote from the Qurʾān, verse 59:24. Part 3: The section opens with a limited diagram of the evolutionary tree, portraying progressions from fish to dinosaurs to birds to mammals to primates. The video suggests that if evolution were true, there would have to be intermediary forms, which would be half fish and half reptile, for instance. The Cambrian period (which the video says was 500-530 million years ago, although the generally accepted period is 540-485 million years ago) is presented as “the oldest stratum in which fossils have been found” (39:00), although it also suggests that older fossils of unicellular organisms have been found. The video states that “Cambrian species came into existence all of a sudden without any ancestors” (40:50). The video uses the example of the coelacanth as a creature that has not changed over millions of years (44:50). Another potential transitional form that is presented to be debunked is the Archaeopteryx , which has been suggested as intermediate between reptiles and birds (46:10). The video then turns to the evolution of primates, including humans. It begins a discussion of Australopithecus [afarensis], which the video suggests is “merely an extinct ape species” (51:20). It presents a selection of the Homo species and suggests that representations of these earlier species is “propaganda” (53:00), showing various representations of the zinjanthropus [now known as Paranthropus boisei] as an example (56:10). The video then surveys some of the faked “fossils” from the twentieth century, such as Piltdown man, Ramapithecus, and “Nebraska man”, Hesperopithecus haroldcookii , suggesting that these are the best fossils that can be presented. The section closes with a reminder that Allah is the one and only Divine Creator.

    Authorities mentioned: Part 1 Charles Darwin (d. 1882), Karl Marx (d. 1883), Louis Pasteur (d. 1895), Alexandr Oparin (d. 1980), Stanley Miller (d. 2007), Jeffery Bada (b. 1942), Sir Frederick Hoyle (d. 2001), James Watson (b. 1987), Francis Crick (d. 2004) Part 2 Charles Darwin, Jean-Baptiste Lamarck (d. 1829), Gregor Mendel (d. 1884), Ernst Mayr (d. 2005), Theodosius Dobzhansky (d. 1975), Julian Huxley (d. 1975), Colin Patterson (b. 1933), Richard Dawkins (b. 1941) Part 3 Charles Darwin, Derek Ager (d. 1993), Richard Dawkins, Mark Czarnecki , Stephen Jay Gould (d. 2002), Raymond Dart (d. 1988), Lord Solly Zuckerman (d. 1993), Charles Oxnard (d. 1997), Richard Leakey (b. 1944), Earnest Hooton (d. 1954)

    Verses of the Qurʾān mentioned in the video: 59:24, 82:6-8

    The video lists three entities involved in its production: IPCI Islamic Vision (Birmingham, UK), Okur Production (Istanbul, Turkey), and SKD Bavaria Verlag (Munich, Germany). Although the video does not give a publication date, internal evidence suggests that it was done in the late 1990s (“as we leave the twentieth century”, min 10:50).

    Evaluation:

    The material on Islam is within the bounds of what Muslims have historically understood as acceptable.

    There are a number of problems here. Intelligent Design and irreducible complexity are not considered viable theories based on the current evidence among a majority of evolutionary biologists. Generally speaking, evolutionary theory does not engage in theories about abiogenesis (the origins of life from non-living materials). There are a variety of sources one might examine to consider a scientific response to the common Intelligent Design constructions presented here. For a general discussion of evolution, see Neil Shubin’s 2009 lecture , “Finding Your Inner Fish”. This lecture also provides a thorough discussion of his work with a single fossil, seeing it through an evolutionary transition, discrediting the assertion that the fossil record does not hold evidence of transitions.

    For a complete discussion of the representations of Intelligent Design generally, see NOVA’s Judgment Day: Intelligent Design on Trial (2007) or the producer’s statement from NOVA. For teaching resources on the topic, see the National Center for Science Education’s site . The video includes a front bumper for the SRF, or Science Research Foundation .

    Although there is limited historical material here, it must be noted that the video does not adequately survey the spectrum of possible material, selecting quotes that generally distort Darwin, for instance, or using outdated science as if it is still considered current. None of the material should be considered factual without comparing it to a solid textbook like Zimmer C. and Emlen DJ. (2013) Evolution: Making Sense of Life.


    Grand Canyon Unconformities –and a Cambrian Island

    A prominent ledge punctuates the landscape towards the bottom of the Grand Canyon. It’s the Tapeats Sandstone, deposited during the Cambrian Period about 520 million years ago, when the ocean was beginning to encroach on the North American continent, an event called the Cambrian Transgression. Above the ledge, you can see more than 3000 feet of near-horizontal sedimentary rocks, eroded into cliffs and slopes depending on their ability to withstand weathering and erosion. These rocks, deposited during the rest of the Paleozoic Era, are often used to demonstrate the vastness of geologic time–some 300 million years of it.

    View of the Grand Canyon from the South Rim trail. Arrows point to the Tapeats Sandstone.

    But the razor-thin surface between the Tapeats and the underlying Proterozoic-age rock reflects the passage of far more geologic time –about 600 million years where the Tapeats sits on top of the sedimentary rocks of the Grand Canyon Supergroup. Those rocks are easy to spot on the photo above because they contain the bright red rock called the Hakatai Shale. Even more time passed across the surface where the Tapeats sits on top of the 1.7 billion year old metamorphic basement rock. You can put your thumb on the basement and a finger on the Tapeats –and your hand will span 1.2 billion years! Read more&hellip

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    500-Million-Year-Old Embryos Fossilized in Rare Find

    Tiny, spherical fossils found in southern China appear to be the embryos of a previously unknown animal.

    The fossils come from the Cambrian, a period dating from 540 million to 485 million years ago and known for an explosion of diversity. Some of the organisms that appeared during the Cambrian, such as the bug-like trilobite, had exoskeletons and other hard parts that fossilized nicely. Others, including sponges and worms, were made of soft tissue that rarely preserves.

    Researchers Jesse Broce of Virginia Tech, James Schiffbauer of the University of Missouri and their colleagues were searching for these rare soft-tissue fossils in limestone from the Hubei province of southern China when they found something even more rare: tiny spheres, including some with polygonal patterns on their surfaces. These itsy-bitsy fossils are most likely fossilized embryos, the researchers report in the March issue of the Journal of Paleontology. The fossils come from the third stage of the Cambrian, dating back to around 521 million to 541 million years ago. [See Images of a Giant Cambrian Creature]

    "We found over 140 spherically shaped fossils, some of which include features that are reminiscent of division-stage embryos, essentially frozen in time," Schiffbauer said in a statement.

    The researchers began their investigation by attempting to dissolve fossils out of the limestone from China's Shuijingtuo formation with acid, but that method seriously damaged or destroyed the spherical fossils. Researchers then hand-chiseled the rock into millimeter- or centimeter-sized chunks, exposing the fossil surfaces manually.

    From there, the researchers investigated the spheres with a variety of techniques, including slicing them into thin sections, which can be viewed under a microscope. The scientists also imaged the fossils with X-ray and scanning electron microscopy and X-ray techniques.

    The results showed specimens with a phosphate-rich envelope surrounding a ball of calcite. (The organic compounds that once made up the embryos have long since mineralized.) Some of the spheres had polygonal patterns that look very similar to those seen on fossilized embryos from Markuelia, a Cambrian worm-like creature. The researchers believe that these specimens are blastulas, which are an early, multicellular stage of embryonic development.

    It remains a mystery what these embryos would have grown up to become. Fossilized embryos from a variety of species pop up occasionally in the fossil record, from a 380-million-year old fish with an embryo still in her belly to dinosaur embryos still curled up inside their eggs.


    The Cambrian of Arkansas

    Our tour of Arkansas fossils and geology should begin, like any tour, at the beginning. The oldest rocks found in Arkansas in which fossils may be found were formed in the Cambrian Period, the earliest part of the Paleozoic Era. When the Paleozoic Era was first named, it began with the rocks containing the oldest known fossils. We now know of fossils far older than that. Nevertheless, it marks a good starting point for rocks in which fossils become commonly found and are easily recognizable. So while Arkansas does not have the earliest fossils, we do have fossils dating back through most of the history of life once hard parts developed.

    Painting by D.W. Miller of the Cambrian world as seen in the Burgess Shale

    The Cambrian Period started about 540 million years ago and lasted until 485 million years ago. During that time, while the land was mostly barren, the seas were full of life. Much of what people know about the Cambrian comes from the Burgess Shale in Canada, possibly the best known example of a lagerstätten, a fossil site rich in either fossil diversity or exceptional preservation, of which the Burgess Shale has both. From the Burgess Shale and other localities, we know that the Cambrian saw the rise of most of the major groups of animals we see today. In addition to the comb jellies, sponges, algae and anemones, brachiopods and bristle worms, velvet worms and crinoids the Cambrian also arthropods of several kinds, most in particular the trilobites, the first chordates like Pikaia, and bizarre creatures like Anomalocaris and Hallucigenia.

    The rise of such a diversity of animal life during the Cambrian has been termed the Cambrian Explosion, leading some people to assume it appeared suddenly and without precedent. In truth, the Cambrian “explosion” took tens of millions of years and was preceded by a diverse fauna known as the Ediacaran or Vendian fauna, which first appeared almost 100 million years earlier. The end of the “Garden of Ediacara” and the rise of the Cambrian fauna is thought to have come about due to the evolution of the first predators, necessitating hard shells for defense and hard claws and teeth to kill prey.

    Purple represents area Collier Shale can be seen.

    The only place in Arkansas to find Cambrian rocks is in the Collier Shale, which was formed in the Cambrian through the Lower Ordovician.

    Outcrops for the Collier Shale are limited to a small set of ridges in the Ouachita Mountains, within Montgomery County between Caddo Gap and Mt. Ida, just to the east of state Highway 27. However, most of this area is part of the Ouachita National forest and is ILLEGAL TO COLLECT anything without a permit.

    The Collier Shale is a large unit at least 1000 feet thick formed mostly of gray to black clay shale that was intensely crumpled during the formation of the Ouachitas. Interspersed within the shale are thin layers of black chert, which together indicate a deep water environment. However, there are also thin layers of dark gray to black limestone, which contain pebbles of chert, limestone, quartz, and even sandstone. It is thought that these layers initially formed in shallower water on the continental shelf before some event caused them to slide off the continental slope into the abyss.

    Housia sp. British Columbia

    The Collier Shale is not known for abundant fossils, but it does have some. In the Cambrian section of the formation, several genera of trilobites have been found, chiefly of the groups known as Asaphida and Ptychopariida. For more information on trilobites and the different types, try the Fossilmuseum.net and Trilobites.info websites. The trilobite genera found in the Collier Shale have been from what is known as the Elvinia and Taenicephalus Zones. These are specific groups of trilobite genera that, when found together, allow the age of the rocks to be determined using correlative dating. These groups, or assemblages, of genera have been found in other parts of the world in rocks that have been able to be dated using rigorous and independent methods, such as radiometric dating. We know that rocks elsewhere in the world containing these fossils are roughly between 490 and 500 million years old, indicating the rocks forming this part of the Collier Shale are the same age. This conclusion is supported by fossils in the rock units overlying this part of the Collier matching those found in rock units over similar rock units of known age elsewhere. The trilobites in the Collier are found in the lower part of the formation. The upper part of the Collier contains fossils known as conodonts, but they are Ordovician in age and will be discussed later.

    Trilobite images from www.fossilmuseum.net and www.trilobites.info. The Cambrian painting by Miller can be found at http://paleobiology.si.edu/burgess/cambrianWorld.html, along with more Cambrian information. The map of the Collier Shale can be found at www.geology.ar.gov and the continental shelf image is from kids.britannica.com.

    Hart, W. D., J. H. Stitt, S. R. Hohensee, and R. L. Ethington. 1987. Geological implications of Late Cambrian trilobites from the Collier Shale, Jessieville area, Arkansas. Geology 15:447–450.

    Hohensee, S. R. Stitt, J. H. 1989. Redeposited Elvinia zone Upper Cambrian trilobites from the Collier Shale, Ouachita Mountains, west-central Arkansas. Journal of Paleontology 63(6): 857-879

    Loch , J.D. and J.F. Taylor. 2004. New trilobite taxa from Upper Cambrian microbial reefs in the central Appalachians. Journal of Paleontology 78(3):591-602. Online publication date: 1-May-2004.

    UPDATE: I thought I would add a little more information about the “Cambrian Explosion,” or as Dr. Donald Prothero calls it, the “Cambrian slow fuse.” The reason for this is because of how long it really took for multicellular life to develop. We have evidence for the earliest life going back over 3.5 billion years, but the earliest agreed upon multicellular life appeared in the Ediacaran fauna (Grypania is a possible multicellular organism dating back 2.1 billion years, but may not be a true multicellular organism and really a colonial organism). The diagram to the right (click to enlarge) is from Prothero’s book, Evolution: What the fossils Say and Why it Matters, and reproduced on a review he wrote of another book. In the diagram, he shows the Ediacaran as starting about 600 million years ago, but now most researchers peg that to about 635 million years ago, so the slow fuse is actually even longer than he shows. The Collier Shale in Arkansas is in the late Cambrian, so as you can see, several other groups are already present. The fact that we have thus far only found trilobites means that we may yet find more diverse types of fossils, so keep looking (and if you find anything, let us know)!


    500-million-year-old embryo fossils a rare and mysterious find

    Tiny, spherical fossils found in southern China appear to be the embryos of a previously unknown animal.

    The fossils come from the Cambrian, a period dating from 540 million to 485 million years ago and known for an explosion of diversity. Some of the organisms that appeared during the Cambrian, such as the bug-like trilobite, had exoskeletons and other hard parts that fossilized nicely. Others, including sponges and worms, were made of soft tissue that rarely preserves.

    Researchers Jesse Broce of Virginia Tech, James Schiffbauer of the University of Missouri and their colleagues were searching for these rare soft-tissue fossils in limestone from the Hubei province of southern China when they found something even more rare: tiny spheres, including some with polygonal patterns on their surfaces. These itsy-bitsy fossils are most likely fossilized embryos, the researchers report in the March issue of the Journal of Paleontology. The fossils come from the third stage of the Cambrian, dating back to around 521 million to 541 million years ago. [See Images of a Giant Cambrian Creature]

    "We found over 140 spherically shaped fossils, some of which include features that are reminiscent of division-stage embryos, essentially frozen in time," Schiffbauer said in a statement.

    The researchers began their investigation by attempting to dissolve fossils out of the limestone from China's Shuijingtuo formation with acid, but that method seriously damaged or destroyed the spherical fossils. Researchers then hand-chiseled the rock into millimeter- or centimeter-sized chunks, exposing the fossil surfaces manually.

    From there, the researchers investigated the spheres with a variety of techniques, including slicing them into thin sections, which can be viewed under a microscope. The scientists also imaged the fossils with X-ray and scanning electron microscopy and X-ray techniques.

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    The results showed specimens with a phosphate-rich envelope surrounding a ball of calcite. (The organic compounds that once made up the embryos have long since mineralized.) Some of the spheres had polygonal patterns that look very similar to those seen on fossilized embryos from Markuelia, a Cambrian worm-like creature. The researchers believe that these specimens are blastulas, which are an early, multicellular stage of embryonic development.

    It remains a mystery what these embryos would have grown up to become. Fossilized embryos from a variety of species pop up occasionally in the fossil record, from a 380-million-year old fish with an embryo still in her belly to dinosaur embryos still curled up inside their eggs.


    Watch the video: The Cambrian explosion