Sometime, in the Devonian, on the floors of shallow, green seas, the fish looked like stones. They lives their lives encased in tight-fitting armor. Bodies locked in cuirass, plackart, and pauldron. Arms: gauntlets. Just a keyhole in the helmet for peeking eyes. Life was lived hidden in an envelope of bone; and the world was only touched through chinks in the walls built against one’s own flesh.
…an extinct genus of antiarch placoderms that lived during the late Devonian period. This genus was largely successful with over 100 species that lived throughout the Devonian. Most members of Bothriolepis were freshwater benthic detritivores, although some were probably able to enter saltwater as well. Some paleontologists hypothesize that live salmon they lived their lives in saltwater and returned to freshwater to breed. Like other antiarches Bothriolepis had a heavily armored head that was attached to a thoratic shield. It also had a long pair of pectoral fins, these fins were likely used to lift it off the bottom as its heavy armor would have made it sink when it lost momentum. It might have also used its fins to throw sediment over itself.
Trilobites appeared in ancient oceans well before life emerged on land. These marine arthropods existed for almost 300 million years, and over 20,000 species have been described so far. In this video, Museum Curator Neil Landman and Field Associates Andy Secher and Martin Shugar discuss trilobites, their unique features, and how fossils are collected and prepared while highlighting a new Museum exhibit that features 15 rare and beautiful trilobite fossils from the Museum’s collection.
Ancient trilobite fossils are now on display in the Museum’s Grand Gallery. The exhibit is made possible thanks to Martin Shugar, M.D., and Andy Secher.
Known from the 525-520 million-year-old Lower Cambrian Chengjiang Lagerstätte, Vetulicola is a member of a strange group of creatures known as vetulicolians. About 9cm (3.5in) long, it’s thought to have been an active swimmer that fed on either plankton or seafloor debris.
And nobody’s sure just what these animals are. They were originally thought to be early limbless arthropods, but more recently opinions have swung in the opposite direct and they’re now considered to be early deuterostomes instead.
The type species, Vetulicola cuneata (Hou, 1987) has a body composed of two distinct parts of approximately equal length. The front part is rectangular with a carapace-like structure of four rigid cuticular plates, with a large mouth at the front end. The posterior section is slender, strongly cuticularised and placed dorsally. Paired openings connecting the pharynx to the outside run down the sides. These features are interpreted as possible primitive gill slits. Vetulicola cuneata could be up to 9 cm long. The Vetulicola are thought to have been swimmers that were either filter feeders or detritivores.
Vetulicola’s taxonomic position is controversial. Vetulicola cuneata was originally assigned to the crustaceans on the assumption that it was a bivalved arthropod like Canadaspis and Waptia, but the lack of legs, the presence of gill slits, and the four plates in the “carapace” were unlike any known arthropod. Shu et al. placed Vetulicola in the new family Vetulicolidae, order Vetulicolida and phylum Vetulicolia, among the deuterostomes. Shu (2003) later argued that the vetulicolians were an early, specialized side-branch of deuterostomes. Dominguez and Jefferies classify Vetulicola as an urochordate, and probably a stem-group appendicularian. In contrast, Butterfield places Vetulicola among the arthropods.
Scientific Illustration in Research Journals PRIMITIVE ECHINODERMS
Stem group Ctenoimbricata [type species Ctenoimbricata spinosa]. Organisms in a stem group are known only from fossils. [More …]
Echinoderms (Phylum Echinodermata) are a phylum of marine animals that includes such well-known animals as starfish, sea urchins, sand dollars, and sea cucumbers. Echinoderms are found at every ocean depth, from the intertidal zone to the abyssal zone.
The phylum contains about 7000 living species, making it the second-largest grouping of deuterostomes after the chordates
Deuterostomes are distinguished from protostomes by their embryonic development: in deuterostomes, the first opening (or blastopore) becomes the anus, while in protostomes it becomes the mouth.
Chordates include the vertebrates, such as birds, fish, mammals, and reptiles.
Echinoderms are also the largest phylum that has no freshwater or terrestrial (land-based) representatives. [Wikipedia] ______________________________________________
TOP Natural mold and latex casts of the holotype of Ctenoimbricata spinosa in dorsal (A, C) and ventral views (B, D).
MIDDLE Radiate and asymmetric echinoderms from the Cambrian showing a selection of primitive echinoderm body plans: A, the ctenocystoid Ctenocystis; B, the cinctan Gyrocystis; C, the helicoplacoid Helicoplacus; D, the solute Coleicarpus; E, the eocrinoid Gogia; F, stromatocystitid edrioasteroid.
BOTTOM Reconstruction of Ctenoimbricata spinosa by paleo illustrator Nobu Tamura. [X]
If you were to wake up one day and find yourself surrounded by these amazing creatures, after first freaking out, you would probably come to the conclusion that you were on some alien world.
But in actuality these are all real organisms from earths distant past - the Cambrian period. Artists and animators have joined forces with paleontologists to produce these visualisations of the various fossils found all over the world.
It is likely planet earth will never see a period like this again, and however horrifying it may have been, that is disappointing.
I have listed the names of the arthropods in the captions of each photo.
Anomalocaris group. going clockwise from the lower left, the animals are: Anomalocaris canadensis, Amplectobelua symbrachiata, Hurdia victoria, Opabinia regalis, Kerygmachela kierkegaardi, Schinderhannes bartelsi, Pambdelurion whittingtoni and Laggania cambria.
Lobopods. Clockwise from top: Microdictyon sinicum, Hallucigenia sparsa, Onychodictyon ferox and Aysheaia pedunculata. Note, by the way, that what appear to be “eyes” on Microdictyon, Hallucigenia and Onychodictyon are actually sclerotized armor plates.
Ancient sea creatures filtered food like modern whales
The animals lived 520 million years ago during the Early Cambrian, a period known as the ‘Cambrian Explosion’ in which all the major animal groups and complex ecosystems suddenly appeared. Tamisiocaris belongs to a group of animals called anomalocarids, a type of early arthropod that included the largest and some of the most iconic animals of the Cambrian period. They swam using flaps down either side of the body and had large appendages in front of their mouths that they most likely used to capture larger prey, such as trilobites.
However, the newly discovered fossils show that those predators also evolved into suspension feeders, their grasping appendages morphing into a filtering apparatus that could be swept like a net through the water, trapping small crustaceans and other organisms as small as half a millimetre in size.
Millions of years before hikers and livestock roamed the Ediacara Hills, the region was home to ancient creatures that mark the birth of animal life. In 1946, geologist Reg Sprigg was exploring the mountainous region in the Flinders Ranges, South Australia, when he came across fossilised imprints of soft-bodied organisms on slabs of quartzite and sandstone. Some had disc-shaped forms like jellyfish, others bore resemblance to worms and arthropods, and others were completely foreign. Sprigg first thought these fossils were from the Cambrian period, but later work showed they were Precambrian—a new geological period was created, set immediately before the Cambrian from 635–541 million years ago, and it was named after the Ediacara Hills. “Ediacara” comes from the Indigenous phrase for “veinlike spring of water”, so it’s pretty fitting that at that time, the region was underwater. The fossils are actually of marine animals, and they existed before animals had skeletons—they represent the oldest complex organisms on Earth. Other fossils of Precambrian soft-bodied organisms had been found before, scattered all over the world, but Ediacara Hills’ collection is the most diverse and most well-preserved. Over 40 different types of organisms have been identified so far, and NASA has even funded some work in the region in the hopes it will shed light on how life might evolve on other planets.
To kick off the blog here is an Ediacaran sea floor. I intend to discuss each of these in more detail over the coming weeks, so right now I am saying nothing (think of it as a tease perhaps). I have this picture as a postcard, so I am rather fond of it.
Also, here is one of my favourite Ediacaran Life images, by Tina Negus (one of the discoverers of Charnia masoni). There are some excellent images of fossils from Charnwood Forest in her photostream.
Located in Hamelin’s Pool, a shallow area of Shark Bay in Western Australia, these odd formations aren’t rocks—they’re stromatolites, and they were built over millennia by single-celled cyanobacteria (also known as blue-green algae). 4,000 to 6,000 years ago, a huge bank of seagrass began to block the tidal flow into Hamelin’s Pool, which meant that the water became twice as salty as the open ocean. Animals like snails and chitons that would usually feed on the algae couldn’t survive, so the blue-green algae began to flourish. Gathered in colonies, they trapped sediment with their sticky surface coatings. This sediment reacted with calcium carbonate in the water and formed limestone, essentially creating a living fossil—this limestone is alive, its top surface layer teeming with active cyanobacteria. The limestone builds up slowly at a rate of about 1mm per year. The stromatolites in Shark Bay are estimated to be between 3,000 and 2,000 years old, but they’re similar to life forms in Precambrian times, 3.5 billion years ago, at the dawn of complex organisms. There are over 50 kinds of cyanobacteria in Shark Bay, and one is thought to have descended from an organism that lived nearly 2 million years ago, making it a part of one of the longest biological lineages.
A hypothesized mechanism for the origin of life, an event called abiogenesis. In this version, called RNA world, small molecules called nucleotides formed in the waters of the early Earth during the Hadean Eon, and polymerized on the surface of clay minerals. These simple chains of RNA could replicate themselves in solution, but only slowly and inaccurately. An RNA molecule developed which would fold into a structure that catalyzed RNA polymerization; a ribozyme. The first ribozymes would replicate their sister strands, and produce copies of themselves and other RNA molecules.
In the same environment, long chains of carbon molecules called phospholipids were formed. These molecules have two parts, the tail, which is hydrophobic, and the head, which is hydrophillic. Because of these properties phospholipids will stick together and form micelles and vesicles in water. Vesicles can absorb RNA nucleotides, concentrating them and creating a space where they can replicate, mutate and evolve. At some point a ribozyme became enclosed within a vesicle, starting a chain reaction that evolved into the multitude of biological forms that we see today.
Because this event occurred more than 3.8 billion years ago, theories about how and where it happened are highly speculative. Possible environments for abiogensis include hydrothermal vents on the ocean floor, hyper saline bubbles of water trapped in ice, radioactive lakes or lagoons on earths surface, and even in space or on another planet, brought to earth through a panspermia event. We have very little molecular evidence of the first cells, but ribozymes and catalytic RNA molecules are embedded in the DNA replication machinery of all life. Because evidence of this event has almost certainly been lost to time, the true mechanisms of the origin of life may remain a mystery to science.