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 Kimberella is a genus of disputable multicellular organism known from fossils that date back to the Ediacaran period, and only one species, K. quadrata, has been recognized. Specimens were first found in Australia's Ediacara Hills, but recent research has concentrated on the numerous finds near the White Sea in Russia, which cover an interval of time from 555-558 Ma. As with many fossils from this time, its evolutionary relationships to other organisms is hotly debated. Palaeontologists initially classified Kimberella as a type of jellyfish, but since 1997 features of its anatomy and its association with scratch marks resembling those made by a radula have been interpreted as signs that it may have been a mollusc. Although some palaeontologists dispute its classification as a mollusc, it is generally accepted as being at least a bilaterian. The classification of Kimberella is important for scientific understanding of the Cambrian explosion: if it was a mollusc or at least a protostome, the protostome and deuterostome lineages must have diverged significantly before 555 Ma. Even if it was a bilaterian but not a mollusc, its age would indicate that animals were diversifying well before the start of the Cambrian. (Read more...)

 Massospondylus is a genus of prosauropod dinosaur from the early Jurassic period, ca. . It was described by Sir Richard Owen in 1854 from remains found in South Africa, and is thus one of the first dinosaurs to have been named. Fossils have since been found in other parts of South Africa, as well as Lesotho and Zimbabwe. Further material from the United States Kayenta Formation, India, and Argentina has been assigned to this genus, but may not belong to Massospondylus. The type, and only universally recognized species, is M. carinatus, although six other species have been named during the past 150 years. Prosauropod systematics have undergone numerous revisions during the last several years, and many scientists disagree where exactly Massospondylus lies on the dinosaur evolutionary tree. Although Massospondylus was long depicted as quadrupedal, a 2007 study found it to be bipedal. It was probably a plant eater (herbivore), although it is speculated that the prosauropods may have been omnivorous. This animal, 4–6 meters (13–20 ft) long, had a long neck and tail, with a small head and slender body. (Read more...)

 Rhynchosaurs (meaning "beaked lizards") were a group of unusual herbivorous quadrupedal archosauromorphs that lived during the Triassic period. Rhynchosaurs ranged in size from the 50 cm long Rhynchosaurus to the 2 meter (6 feet) long Hyperodapedon, with the average size being 1 meter (3.3 feet). Rhynchosaurs were a widespread and worldwide taxon, being found all across the supercontinent of Pangaea. Rhynchosaur fossils have been found in Britain, South Africa, Zimbabwe, Tanzania, Madagascar, India, Brazil, Argentina, Canada and the United States, although they are poorly represented in the Northern Hemisphere fossil record. 15 species are currently regarded as valid, and another five are valid taxa still in need of a name. In some fossil assemblages, several taxa lived alongside one another, as evidenced by the four contemporaneous species were contemporaneous in the Upper Triassic Santa Maria Formation of Brazil. Rhynchosaurs went extinct during the Permian-Triassic extinction event that marked the end of the Carnian stage of the Late Triassic. Rhynchosaur fossils are very abundant in some assemblages (in some fossil localities accounting for 40 to 60% of specimens found) and the anatomy and ontogeny of a few species is comparatively well known. Early primitive forms like Mesosuchus and Howesia were more typically lizard-like in build, and had skulls rather similar to the early diapsid Younginia, except for the beak and a few other features. (Read more...)

 There have been a number of potential species assigned to Allosaurus, a carnosaurian dinosaur, since its description in 1877 by Othniel Charles Marsh, but only a handful are still regarded as valid. Allosaurus was originally described from material from the Upper Jurassic Morrison Formation of the western United States of America; the type species A. fragilis became one of the best-known species of dinosaur. The genus Allosaurus was part of the Marsh/Cope "Bone Wars" of the late 1800s, and its taxonomy became increasingly confused due to the competition, with several genera and species named by Cope and Marsh now regarded as synonyms of Allosaurus or A. fragilis. Since the description of Allosaurus, scientists have proposed additional species from such far-flung locales as Portugal, Siberia, Switzerland, and Tanzania, Australia and unnamed remains from China have also been assigned to the genus at one time or another. It is unclear how many species of Allosaurus there were. Seven species have been considered potentially valid since 1988. There are also at least ten dubious or undescribed species that have been assigned to Allosaurus over the years, along with the species belonging to genera now sunk into Allosaurus. (Read more...)

 The Bone Wars is the name given to a period of intense fossil speculation and discovery during the Gilded Age of American history, marked by a heated rivalry between Edward Drinker Cope and Othniel Charles Marsh. Each of the two palaeontologists used underhanded methods to out-compete the other in the field, resorting to bribery, theft, and destruction of bones. The scientists also attacked each other in scientific publications, attempting to ruin the other's credibility and cut off his funding. Originally colleagues who were civil to each other, Cope and Marsh became bitter enemies after several personal slights between them. Their pursuit of bones led them west to rich bone beds in Colorado, Nebraska, and Wyoming. From 1877 to 1892, both palaeontologists used their wealth and influence to finance their own expeditions and to procure services and fossils from dinosaur hunters. By the end of the Bone Wars, both men exhausted their funds in fueling their intense rivalry. Cope and Marsh were financially and socially ruined by their efforts to disgrace each other, but their contributions to science and the field of palaeontology were massive; the scientists left behind tons of unopened boxes of fossils on their deaths. The feud between the two men led to over 142 new species of dinosaurs being discovered and described. (Read more...)

 Lystrosaurus is an extinct genus of dicynodont therapsid that lived during the Late Permian and Early Triassic periods, around 250 million years ago in what is now Antarctica, India and South Africa. At present 4 to 6 species are recognized, although from the 1930s to 1970s the number of species was thought to be much higher. Lystrosaurus had only two teeth, as with all other dicynodonts, as well as a pair of tusk-like canines. Lystrosaurus is thought to have had a horny beak that was used for biting off pieces of vegetation. Lystrosaurus was a heavily-built, herbivorous animal, approximately the size of a pig. The structure of its shoulders and hip joints suggest that Lystrosaurus moved with a semi-sprawling gait. Lystrosaurus was by far the most common terrestrial vertebrate of the Early Triassic, accounting for as many as 95% of the total individuals in some fossil beds. It has often been suggested that it had anatomical features that enabled it to adapt better than most animals to the atmospheric conditions that were created by the Permian–Triassic extinction event and which persisted through the Early Triassic — low concentrations of oxygen and high concentrations of carbon dioxide. However recent research suggests that these features were no more pronounced in Lystrosaurus than in genera that perished in the extinction or genera that survived but were much less abundant than Lystrosaurus. (Read more...)

 Acrocanthosaurus (meaning 'high-spined lizard') is a genus of theropod dinosaur that existed in what is now North America during the Aptian and early Albian stages of the Early Cretaceous. Like most dinosaur genera, Acrocanthosaurus contains only a single species, A. atokensis. Its fossil remains are found mainly in the U.S. states of Oklahoma and Texas, although teeth attributed to Acrocanthosaurus have been found as far east as Maryland. Acrocanthosaurus was a bipedal predator. As the name suggests, it is best known for the high neural spines on many of its vertebrae, which most likely supported a ridge of muscle over the animal's neck, back and hips. Acrocanthosaurus was one of the largest theropods, approaching 12 meters (40 ft) in length, and weighing up to about 2.40 metric tons (2.65 short tons). Large theropod footprints discovered in Texas may have been made by Acrocanthosaurus, although there is no direct association with skeletal remains. Recent discoveries have elucidated many details of its anatomy, allowing for specialized studies focusing on its brain structure and forelimb function. However, there is still debate over its evolutionary relationships, with some scientists classifying it as an allosaurid, and others as a carcharodontosaurid. Acrocanthosaurus was the largest theropod in its ecosystem and likely an apex predator which possibly preyed on large sauropods and ornithopods. (Read more...)

 Deinosuchus is an extinct relative of the alligator that lived, during the Late Cretaceous period. The first remains were discovered in North Carolina in the 1850s, but it was not until 1909 that the genus was named and described. Additional fragments were discovered in the 1940s and were later incorporated into an influential, though inaccurate, skull reconstruction at the American Museum of Natural History. Knowledge of Deinosuchus remains incomplete, but better cranial material found in recent years has expanded scientific understanding of this massive predator. Although Deinosuchus was far larger than any modern crocodile or alligator—measuring up to 12 m (40 ft) and weighing up to 8.5 metric tons (9.4 short tons)—its overall appearance was fairly similar to its smaller relatives. It had large, robust teeth that were built for crushing, and its back was covered with thick semispherical osteoderms. One study indicates that Deinosuchus may have lived for up to 50 years, growing at a similar rate to that of modern crocodilians, but maintaining this growth over a much longer period of time. (Read more...)

 Kritosaurus (meaning "separated lizard"; sometimes misinterpreted as "noble lizard", in reference to the presumed "Roman nose"; the nasal region was fragmented, disarticulated, and originally restored flat) is an incompletely known but historically important genus of extinct hadrosaurid (duckbilled) dinosaur. It lived about 73 million years ago, during the Late Cretaceous of North and possibly South America. Its taxonomic history is convoluted, also incorporating Gryposaurus, Anasazisaurus, and Naashoibitosaurus; this tangle will remain unresolved until better remains of Kritosaurus are described. Despite the dearth of material, this herbivore appeared in dinosaur books until the 1990s, although what was usually represented was the much more completely known Gryposaurus, then thought to be a synonym. In 1904, Barnum Brown discovered the type specimen (AMNH 5799) of Kritosaurus near Ojo Alamo, San Juan County, New Mexico, United States, while following up on a previous expedition. He initially could not definitely correlate the stratigraphy, but by 1916 was able to establish it as from what is now known as the late Campanian-age De-na-zin Member of the Kirtland Formation. (Read more...)

 Aetosauria, (meaning "Eagle Lizards") is an extinct clade of heavily armored, medium to large-sized Late Triassic quadrupedal archosaurs that were mostly herbivorous. Aetosaurs are widely characterized by their dorsal and ventral surfaces being encased in parallel rows of subrectangular osteoderms, some of which sported spikes in some species. Aetosaurs ranged in size from 1–5 meters (3–16 ft), with the average size being between 2.5–3 meters (8–10 ft). Some of the smallest aetosaurs were Aetosaurus and Coahomasuchus, reaching no more than a meter in length. Aetosaur fossils were first documented by palaeontologist Louis Agassiz (1807-1873) in 1844, although they were originally attributed armored fish, instead of archosaurs. Two distinct subdivisions of aetosaurs are currently recognized, the Desmatosuchinae and the Aetosaurinae, based primarily on differences in the morphology of the bony scutes of the two groups. Aetosaurs first appeared during the Late Carnian epoch of the Late Triassic, roughly the same time that phytosaurs and ornithosuchids appeared. From that point on, they quickly diversified, into various genera, with the most notable being Aetosaurus, Stagonolepis, and Desmatosuchus, and existed for nearly the entirety of the Late Triassic. Aetosaurs quickly became widespread across the the supercontinent Pangaea, with their fossils being found in Europe (Scotland, Germany), India, Northern Africa, North (United States) and South America (Argentina), Greenland and Madagascar. (Read more...)

 85px|left|The "Archaeoraptor" fossil forgery "Archaeoraptor" is the generic name informally assigned in 1999 to a fossil from China in an article published in National Geographic magazine. The magazine claimed that the fossil was a "missing link" between birds and terrestrial theropod dinosaurs. Even prior to this publication there had been severe doubts about the fossil's authenticity. It led to a scandal when it was definitely proven to be a forgery through further scientific study. The forgery was constructed from rearranged pieces of real fossils from different species. Zhou et al. found that the head and upper body actually belong to a specimen of the primitive fossil bird Yanornis. A 2002 study found that the tail belongs to a small winged dromaeosaur, Microraptor, named in 2000. The legs and feet belong to an as yet unknown animal. The "Archaeoraptor" scandal has ongoing ramifications. The scandal brought attention to illegal fossil deals conducted in China. It also highlighted the need for close scientific scrutiny of purported "missing links" published in journals which are not peer-reviewed. The fossil scandal has been used by creationists to cast doubt on evolutionary theory. Although "Archaeoraptor" was a forgery, many true examples of feathered dinosaurs have been found and demonstrate the evolutionary connection between birds and other theropods. (Read more...)

 Crassigyrinus (meaning "thick tadpole") is an extinct genus of carnivorous stem group tetrapod from the Early Carboniferous of Scotland and a possible specimen from Greer, West Virginia. The type specimen was originally described as Macromerium scoticum and lacked a complete skull. With subsequent discoveries, Crassigyrinus is now known from three skulls, one of which is in articulation with a fairly complete skeleton, and a couple of incomplete lower jaws. Crassigyrinus grew up to 1.5 meters in length, coupled with punitive limbs and unusually large jaws. Crassigyrinus is taxonomically enigmatic, having confused palaeontologists for decades with its apparent fish-like and tetrapod features. Some palaeontologists have even considered it as the most basal tetrapod, while others hesitate to even place it within the Tetrapoda superclass. Crassigyrinus had unusually large jaws, enabling it to eat other animals it could catch and swallow. It had two rows of sharp teeth in its jaws, the second row having a pair of fangs. Crassigyrinus had large eyes, suggesting that it was either nocturnal, or lived in very murky water. (Read more...)

 Darwinius is a genus of extinct Adapiformes, a group of basal or stem group primates from the Eocene epoch, 47 million years ago (Lutetian stage) based on dating of the fossil site. The only known fossil, dubbed Ida, was discovered in 1983 at the Messel pit, a disused shale quarry noted for its astonishing fossil preservation, near the village of Messel, about 35 kilometers (22 mi) southeast of Frankfurt am Main. The fossil, divided into a positive and negative slab after the amateur excavation and sold separately, was not reassembled until the early months of 2007, and formally published in 2009. The fossil is of a juvenile female, approximately 58 cm (23 in) overall length, and it is estimated that Ida died at about 80–85% of her projected adult body and limb length. The scientists who published the initial paper on Darwinius described it as a significant transitional form between early primitive primates and the later prosimian and simian lineages. The creature appeared superficially similar to a modern lemur. The fossil is classified as lying near the separation of two major primate clades: one leading to the prosimians, the other to the anthropoid monkeys and, eventually, to the great apes, including Homo sapiens. However, concerns have been raised about the claims made about its relative importance, and the publicizing of the fossil before adequate information was available for scrutiny by other scientists. (Read more...)

 Dromaeosaurids are a family of extinct bird-like theropod dinosaurs. They were small to medium-sized, feathered carnivores that flourished during the Cretaceous period. In informal usage they are often called "raptors" (after Velociraptor), a term popularized by the film Jurassic Park and have become iconic for their enlarged "sickle claw" on the second toe. The name Dromaeosauridae means 'running lizards', from Greek dromeus (δρομευς) meaning 'runner' and sauros (σαυρος) meaning 'lizard'. Dromaeosaurid fossils have been found in North America, Europe, North Africa, Japan, China, Mongolia, Madagascar, Argentina, and Antarctica. They first appeared in the mid-Jurassic period (Bathonian stage, 167 Ma) and survived until the end of the Cretaceous (Maastrichtian stage, 65.5 Ma), existing for over 100 million years, up until the Cretaceous-Paleogene extinction event. The presence of dromaeosaurs as early as the Middle Jurassic has been confirmed by the discovery of isolated fossil teeth, though no dromaeosaurid body fossils have been found from this epoch. There is also a large body of evidence showing that dromaeosaurids were covered in feathers. Some dromaeosaurid fossils preserve long, pennaceous feathers on the hands and arms (remiges) and tail (rectrices), as well as shorter, down-like feathers covering the body. (Read more...)

 Nanotyrannus (meaning "small tyrant") is a problematic genus of tyrannosaurid dinosaur, and is possibly a juvenile specimen of Tyrannosaurus. Nanotyrannus is the smallest known tyrannosaurid and was one of the last tyrannosaurids to exist before the end-Cretaceous mass extinction, the K-T event. The genus is represented only by a small skull that was discovered by Charles W. Gilmore in 1942 and described in 1946 as a specimen of Gorgosaurus lancensis (now known as Albertosaurus). In 1988, the specimen was re-described by Robert T. Bakker, Phil Currie, and Michael Williams, the late curator of palaeontology at the Cleveland Museum of Natural History, where the original specimen was housed and is currently on display. Opinions continue to remain divided on the validity of N. lancensis. Nanotyrannus can be a possible juvenile of a tyrannosaur that is closely related to Tyrannosaurus and the adult of this animal is yet to be identified, or it really is a juvenile Tyrannosaurus. In either case, an adult Nanotyrannus has to be discovered or a juvenile Tyrannosaurus of the same size as Nanotyrannus but morphologically distinct from it in order to fully resolve this debate. Many palaeontologists consider the skull to belong to a juvenile Tyrannosaurus rex. (Read more...)

 Spinosaurus (meaning "spine lizard") is a genus of theropod dinosaur which lived in what is now North Africa, sometime during the Albian and Cenomanian stages of the Cretaceous period, about. This genus was first known from Egyptian remains discovered in the 1910s and described by German palaeontologist Ernst Stromer. These original remains were destroyed in World War II, but additional skull material has come to light in recent years. It is unclear whether one or two species are represented in the described fossils. The best known species is S. aegyptiacus from Egypt, although a potential second species, S. marocannus, has been recovered from Morocco. The distinctive spines of Spinosaurus, which were long extensions of the vertebrae, grew up to 2 meters (7 ft) long and were likely to have had skin connecting them, forming a sail-like structure, although some authors have suggested that they were covered in muscle and formed a hump or ridge. Multiple functions have been put forward for this structure, including thermoregulation and display. According to recent estimates, Spinosaurus is the largest of all known carnivorous dinosaurs, even larger than Tyrannosaurus and Giganotosaurus. These estimates suggest that it was around 16 to 18 meters (52 to 59 ft) in length and 7 to 9 tonnes (7.7 to 9.9 short tons) in weight. (Read more...)

<div style="width:55%; background-color:#f5fffa; border:1px solid #cef2e0;padding:1em;padding-top:0.5em; color: black"> Herrerasaurus (meaning "Herrera's lizard", after the name of the rancher who discovered the first fossil of the animal) was one of the earliest dinosaurs. All known specimens of this carnivore have been discovered in rocks of early Carnian age (late Triassic, around ) in northwestern Argentina. The type species, Herrerasaurus ischigualastensis, was described by Osvaldo Reig in 1963 and is the only species assigned to the genus. The names Ischisaurus and Frenguellisaurus are synonymous with Herrerasaurus. For many years, the classification of Herrerasaurus was unclear, as the animal was initially known from very fragmentary remains; it has been hypothesized to be a basal theropod, a basal sauropodomorph, a basal saurischian, or not a dinosaur at all. However, with the discovery of a mostly complete skeleton and skull in 1988, Herrerasaurus has been classified as either an early theropod or an early saurischian in at least five recent reviews of theropod evolution. Herrerasaurus is a medium-sized bipedal member of the Herrerasauridae, a group of similar animals which were among the earliest of the dinosaurian evolutionary radiation. (Read more...)

<div style="width:55%; background-color:#f5fffa; border:1px solid #cef2e0;padding:1em;padding-top:0.5em; color: black"> Hupehsuchia is an order of enigmatic diapsid marine reptiles belonging to the class Sauropsida. The order was short-lasting, with a temporal range restricted to the Spathian age of the late Olenekian, spanning only a few million years of the Early Triassic. The order gets its name from Hubei Province, China, from which many specimens have been found. Of the entire order, Nanchangosauridae is the only recognized family. Hupehsuchians display an unusual combination of characteristics with other derived marine reptiles, including mosasaurs and ichthyosaurs, including polydactyly, narrow skull, and vivipary. The order consists of two genera, Hupehsuchus and Nanchangosaurus, of which, the former is the type genus. Determining the exact classification and phylogeny of this group remains difficult, and may be attributed to the limited knowledge of the fossil record of diapsid reptiles in the Late Permian and Early Triassic, as well as the great amount of convergence exhibited by secondarily aquatic reptiles. (Read more...)

<div style="width:55%; background-color:#f5fffa; border:1px solid #cef2e0;padding:1em;padding-top:0.5em; color: black"> The small shelly fauna are mineralized fossils, many only a few millimetres long, with a nearly continuous record from the latest stages of the Ediacaran to the end of the Early Cambrian period. They are very diverse, and there is no formal definition of "small shelly fauna" or "small shelly fossils". Almost all are from earlier rocks than more familiar fossils such as trilobites. Since most SSFs were preserved by being covered quickly with phosphate and this method of preservation is mainly limited to the Late Ediacaran and Early Cambrian periods, the animals that made them may actually have arisen earlier and persisted after this time span. Some of the fossils represent the entire skeletons of small organisms, including the mysterious Cloudina and some snail-like molluscs. However, the bulk of the fossils are fragments or disarticulated remains of larger organisms, including sponges, molluscs, slug-like halkieriids, brachiopods, echinoderms, and onychophoran-like organisms that may have been close to the ancestors of arthropods. (Read more...)

<div style="width:55%; background-color:#f5fffa; border:1px solid #cef2e0;padding:1em;padding-top:0.5em; color: black"> Protoavis (meaning "first bird") is a problematic taxon of archosaurian whose fossils have been recovered from Late Triassic Norian stage deposits near Post, Texas. Much controversy remains over the animal, with many different interpretations of what Protoavis actually is existing. When it was first described, the fossils were ascribed to a primitive bird which, if the identification is valid, would push back avian origins some 60-75 million years. The original describer of Protoavis texensis, Sankar Chatterjee of Texas Tech University, interpreted the type specimen to have come from a single animal, specifically a 35 cm tall bird that lived in what is now Texas, USA, between. Though it existed far earlier than Archaeopteryx, its skeletal structure is allegedly more bird-like. However, this description of Protoavis assumes that Protoavis has been correctly interpreted as a bird. Almost all palaeontologists doubt that Protoavis is a bird, or that all remains assigned to it even come from a single species, because of the circumstances of its discovery and unconvincing avian synapomorphies in its fragmentary material. (Read more...)

<div style="width:55%; background-color:#f5fffa; border:1px solid #cef2e0;padding:1em;padding-top:0.5em; color: black"> Tarbosaurus is a genus of tyrannosaurid theropod dinosaur that flourished in Asia between, at the end of the late Cretaceous period. Fossils have been recovered in Mongolia with more fragmentary remains found further afield in parts of China. Some experts contend that this species is actually an Asian representative of the North American genus Tyrannosaurus; if true, this would invalidate the genus Tarbosaurus altogether. Like most known tyrannosaurids, Tarbosaurus was a large bipedal predator, weighing more than a ton and equipped with dozens of large, sharp teeth. It had a unique locking mechanism in its lower jaw and the smallest forelimbs relative to body size of all tyrannosaurids, renowned for their disproportionately tiny, two-fingered forelimbs. Tarbosaurus lived in a humid floodplain criss-crossed by river channels. In this environment, it was an apex predator at the top of the food chain, probably preying on other large dinosaurs like the hadrosaur Saurolophus or the sauropod Nemegtosaurus. Tarbosaurus is very well-represented in the fossil record, known from dozens of specimens, including several complete skulls and skeletons. These remains have allowed scientific studies focusing on its phylogeny, skull mechanics, and brain structure. (Read more...)

<div style="width:55%; background-color:#f5fffa; border:1px solid #cef2e0;padding:1em;padding-top:0.5em; color: black"> The Ediacaran biota consisted of enigmatic tubular and frond-shaped sessile (stationary) organisms which lived during the Ediacaran Period (ca. ). Trace fossils of these organisms have been found worldwide, and represent the earliest known complex multicellular organisms. The Ediacara biota first appeared as the Earth thawed from the Cryogenian period's extensive glaciers, and largely disappeared contemporaneous with the rapid appearance of biodiversity known as the Cambrian explosion, Most currently existing body-plans of animals made first appearances in the fossil record of the Cambrian. The Cambrian biota completely replaced the organisms that dominate the Ediacaran fossil record. The organisms of the Ediacaran Period first appeared around and flourished until the cusp of the Cambrian  when the characteristic communities of fossils vanished. While rare fossils that may represent survivors have been found as late as the Middle Cambrian the earlier fossil communities disappear from the record at the end of the Ediacaran leaving only curious fragments of once-thriving ecosystems. Multiple hypotheses exist to explain the disappearance of this biota, including preservation bias, a changing environment, the advent of predators and competition from other life-forms. (Read more...)

<div style="width:55%; background-color:#f5fffa; border:1px solid #cef2e0;padding:1em;padding-top:0.5em; color: black"> Cloudinidae is an early metazoan family containing the genus Cloudina, which lived during the Late Ediacaran period and became extinct at the base of the Cambrian. They formed millimeter-scale conical fossils consisting of calcareous cones nested within one another; the appearance of the organism itself remains unknown. The name Cloudina honors the 20th century geologist and palaeontologist Preston Cloud. Cloudinids had a wide geographic range, reflected in the present distribution of localities in which their fossils are found, and are an abundant component of some deposits. They never appear in the same layers as soft-bodied Ediacaran biota, but the fact that some sequences contain Cloudinids and Ediacaran biota in alternating layers suggests that these groups had different environmental preferences. It has been suggested that Cloudinids lived embedded in microbial mats, growing new cones to avoid being buried by silt. However no specimens have been found embedded in mats, and their mode of life is still an unresolved question. Cloudinids are among the earliest and most abundant of the small shelly fossils with mineralized skeletons, and therefore feature in the debate about why such skeletons first appeared in the Late Ediacaran. (Read more...)

Recently promoted: Ediacaran biota — Tarbosaurus — Protoavis

To do

 * 1) Darwinopterus
 * 2) Evolution of crurotarsans
 * 3) Fossilisation
 * 4) Hadrosaur diet
 * 5) Tyrannosauridae
 * 6) Tyrannosauroidea
 * 7) Ceratopsia
 * 8) Dinosaur mummies
 * 9) Birds Came First
 * 10) Benjamin Franklin Mudge
 * 11) Cambrian explosion
 * 12) Pterosauria
 * 13) Edmontosaurus
 * 14) Specimens of Tyrannosaurus
 * 15) Gorgosaurus
 * 16) Mary Anning
 * 17) Batrachotomus
 * 18) History of paleontology
 * 19) Opabinia
 * 20) Othnielosaurus
 * 21) Archaeopteryx
 * 22) Homo floresiensis
 * 23) Albertosaurus
 * 24) Allosaurus
 * 25) Chicxulub crater
 * 26) Compsognathus
 * 27) Cretaceous–Tertiary extinction event
 * 28) Daspletosaurus
 * 29) Diplodocus
 * 30) Lambeosaurus
 * 31) Majungasaurus
 * 32) Psittacosaurus
 * 33) Stegosaurus
 * 34) Styracosaurus
 * 35) Thescelosaurus
 * 36) Alioramus
 * 37) Abelisauridae
 * 38) Coelurus
 * 39) Heterodontosauridae
 * 40) Plateosaurus