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44-612: Castorocauda is an extinct, semi-aquatic, superficially otter -like genus of docodont mammaliaforms with one species, C. lutrasimilis . It is part of the Yanliao Biota , found in the Daohugou Beds of Inner Mongolia , China dating to the Middle to Late Jurassic . It was part of an explosive Middle Jurassic radiation of Mammaliaformes moving into diverse habitats and niches . Its discovery in 2006, along with

88-538: A tactile sense, was an ancestral trait of mammals. Mammals preserved with fur from the Chinese Yixian Formation show little hair on the tail, whereas the fur outline preserved on the Castorocauda tail was 50% wider than the pelvis . The first quarter is covered by guard hairs , the middle half by scales and little hair cover and the last quarter by scales with some guard hair. Beavers have

132-517: A 2010 review of docodonts, Docodonta was split into Docodontidae , Simpsonodontidae and Tegotheriidae , with Castorocauda considered incertae sedis with indeterminate affinities . Simpsonodontidae is now considered to be paraphyletic and thus invalid, and Castorocauda appears to have been most closely related to Dsungarodon , which came from the Junggar Basin of China and probably ate plants and soft invertebrates. Castorocauda

176-511: A British man in his 60s during an early morning walk in Singapore Botanic Gardens . Despite weighing over 200 pounds, he was trampled and bitten and could not stand up without help from a nearby rescuer. The man speculated that another runner might have stepped on one of the animals earlier, and wished that there could be more lighting installed at that location. Norse mythology tells of the dwarf Ótr habitually taking

220-505: A bevy, family, lodge, romp, or raft when in water, indicating their social and playful characteristics. Otters are known for their distinct feces, termed spraints , which can vary in smell from freshly mown hay to putrefied fish. Otters exhibit a varied life cycle with a gestation period of about 60–86 days, and offspring typically stay with their family for a year. They can live up to 16 years, with their diet mainly consisting of fish and sometimes frogs , birds, or shellfish , depending on

264-466: A critical point which allowed for a massive expansion into different habitats. Castorocauda is the earliest known aquatic mammaliaform, pushing back the first appearance of mammaliaform aquatic adaptations by over 100 million years. The teeth interlocked while biting, suggesting that they were strictly used for gripping; the recurved molars were likely used to hold slippery prey; and the teeth shapes are convergent with seals and Eocene whales, suggesting

308-566: A high metabolic rate for warmth. Otter-human interactions have varied over time, with otters being hunted for their pelts , used in fishing practices in southern Bangladesh, and occasionally attacking humans, though such incidents are rare and often a result of provocation. Otters hold a place in various cultures' mythology and religion, symbolizing different attributes and stories, from Norse mythology to Native American totems and Asian folklore, where they are sometimes believed to possess shapeshifting abilities. The word otter derives from

352-573: A rocky cairn, more common in Scotland. It is lined with moss and grass. After one month, the pup can leave the holt and after two months, it is able to swim. The pup lives with its family for approximately one year. Otters live up to 16 years; they are by nature playful, and frolic in the water with their pups. Its usual source of food is fish, and further downriver, eels, but it may sample frogs and birds. Otters have long, slim bodies and relatively short limbs. Their most striking anatomical features are

396-419: A similar ecological standing. Based on these, its adaptations to swimming and digging and its large size, Castorocauda was probably comparable to the modern day platypus , river otters and similar semi-aquatic mammals in ecology and fed primarily on fish ( piscivory ). The Daohugou Beds also include several salamanders , numerous pterosaur species (of which many likely were piscivorous), several insects,

440-467: A straight row, and interlocked during biting. This feature is similar to the ancestral condition in Mammaliaformes (such as in triconodonts ) but is a derived character (it was specially evolved instead of inherited) in Castorocauda . The lower jaw contained 4 incisors , 1 canine , 5 premolars and 6 molars. The forelimbs of Castorocauda are very similar to those of the modern platypus:

484-686: A very similar tail. Evidence of fur and assumed heightened tactile senses indicate it had a well-developed neocortex , a portion of the brain unique to mammals which, among other things, controls sensory perception . Adelobasileus Sinoconodon Morganucodon Megazostrodon Haramiyavia Thomasia Megaconus Eleutherodon Sineleutherus Sibirotherium Tegotherium Hutegotherium Itatodon Krusatodon Agilodocodon Simpsonodon Tashkumyrodon Castorocauda Dsungarodon Borealestes Docofossor Docodon Haldanodon Hadrocodium Crown mammals Castorocauda

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528-487: Is a member of the order Docodonta , an extinct group of mammaliaforms . Mammaliaformes includes mammal-like creatures and the crown mammals (all descendants, living or extinct, of the last common ancestor of all living mammals). Docodonts are not crown mammals. When Castorocauda was first described in 2006, it was thought to be most closely related to the European Krusatodon and Simpsonodon . In

572-465: Is due to hunting to supply the demand for skins. For many generations, fishermen in southern Bangladesh have bred smooth-coated otters and used them to chase fish into their nets. Once a widespread practice, passed down from father to son throughout many communities in Asia, this traditional use of domesticated wild animals is still in practice in the district of Narail , Bangladesh. A 2011 review by

616-528: Is held to be a clean animal belonging to Ahura Mazda in Zoroastrian belief, and taboo to kill. In popular Korean mythology, it is told that people who see an otter ( soodal ) will attract 'rain clouds' for the rest of their lives. In the Buddhist Jataka tales, The Otters and The Wolf, two otters agreed to let a wolf settle their dispute in dividing their caught fish but it was taken away by

660-523: Is part of a Middle Jurassic mammaliaform diversification event, wherein mammaliaforms radiated into a wide array of niches and evolved several modern traits, such as more modern mammalian teeth and middle ear bones. It was previously thought that mammals were small and ground-dwelling until the Cretaceous–Paleogene boundary (K–Pg boundary) when dinosaurs went extinct. The discovery of Castorocauda , and evidence for an explosive diversification in

704-843: The Inner Mongolia region of China, which dates to about 159–164 million years ago (mya) in the Middle to Late Jurassic . It comprises a partial skeleton including an incomplete skull but well-preserved lower jaws, most of the ribs, the limbs (save for the right hind leg), the pelvis and the tail. The remains are so well preserved that there are elements of its soft anatomy and hair. The genus name Castorocauda derives from Latin Castor " beaver " and cauda "tail", in reference to its presumed beaver-like tail. The species name lutrasimilis derives from Latin lutra " otter " and similis "similar", because some aspects of its teeth and vertebrae are similar to modern otters. Castorocauda

748-788: The Old English word otor or oter . This and cognate words in other Indo-European languages ultimately stem from the Proto-Indo-European root *wódr̥ , which also gave rise to the English word "water". An otter's den is called a holt, or couch. Male otters are called dogs or boars; females are called bitches or sows; and their offspring are called pups or cubs. The collective nouns for otters are bevy, family, lodge, romp (being descriptive of their often playful nature), or, when in water, raft. The feces of otters are typically identified by their distinctive aroma,

792-483: The clam shrimp Euestheria and some birdlike dinosaurs. No fish are known from specifically the Daohugou Beds, but the related Linglongta locality contains undetermined ptycholepiformes . Other mammals include the flying-squirrel -like Volaticotherium , the burrowing Pseudotribos , the oldest known eutherian Juramaia . the rat -like Megaconus and the gliding Arboroharamiya . The plant life of

836-444: The giant otter and sea otter are the largest. They have very soft, insulated underfur, which is protected by an outer layer of long guard hairs . This traps a layer of air which keeps them dry, warm, and somewhat buoyant under water. Several otter species live in cold waters and have high metabolic rates to help keep them warm. Eurasian otters must eat 15% of their body weight each day, and sea otters 20 to 25%, depending on

880-405: The humerus during extension of the forearm. Its base is contracted where it joins the body and the narrowest part of the upper end of the ulna. Its posterior surface, directed backward, is triangular, smooth, subcutaneous, and covered by a bursa . Its superior surface is of quadrilateral form, marked behind by a rough impression for the insertion of the triceps brachii ; and in front, near

924-462: The humerus widens towards the elbow ; the forearm bones have hypertrophied (large) epicondyles (where the joint attaches); the radial and ulnar joints are widely separated; the ulna has a massive olecranon (where it attaches to the elbow); the wrist bones are block-like; and the finger bones are robust. Docodontans were likely burrowing creatures and had a sprawling gait , and Castorocauda may have also used its arms for rowing, similar to

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968-536: The subfamily Lutrinae . The 13 extant otter species are all semiaquatic , aquatic , or marine . Lutrinae is a branch of the Mustelidae family , which includes weasels , badgers , mink , and wolverines , among other animals. Otters' habitats include dens known as holts or couches, with their social structure described by terms such as dogs or boars for males, bitches or sows for females, and pups or cubs for offspring. Groups of otters can be referred to as

1012-528: The 1700s, although it may have begun well before then. Early hunting methods included darts, arrows, nets and snares but later, traps were set on land and guns used. There has been a long history of otter pelts being worn around the world. In China it was standard for the royalty to wear robes made from them. People that were financially high in status also wore them. The tails of otters were often made into items for men to wear. These included hats and belts. Even some types of mittens for children have been made from

1056-817: The IUCN/SSC Otter Specialist Group showed that otter attacks reported between 1875 and 2010 occurred most often in Florida , where human and otter populations have substantially increased since 2000, with the majority involving the North American otter. At least 42 instances of attack were found, including one resulting in death and another case of serious injury. Attacking otters had rabies in 36% of anecdotal reports. 80% of otter bite victims do not seek medical treatment. Animal welfare groups say that, unless threatened, otters rarely attack humans. In November 2021, about 20 otters ambushed

1100-531: The Middle Jurassic – such as the appearance of eutriconodontans , multituberculates , australosphenidans , metatherians and eutherians , among others – disproves this notion. This may have been caused by the breakup of Pangaea , which started in the Early to Middle Jurassic and diversified habitats and niches, or modern traits that had been slowly accumulating since mammaliaforms evolved until reaching

1144-801: The Tiaojishan Formation was dominated by cycadeoids (mainly Nilssonia and Ctenis ), leptosporangiate ferns and ginkgophytes and has pollen remains predominantly from pteridophytes and gymnosperms , which indicate a cool temperate and wet climate with distinct wet and dry seasons, possibly with an annual temperature of below 15 °C (59 °F). [REDACTED] Otter Aonyx Enhydra Hydrictis Lontra Lutra Lutrogale Pteronura † Enhydriodon † Algarolutra † Cyrnaonyx † Megalenhydris † Sardolutra † Siamogale † Teruelictis † Satherium † Enhydritherium Otters are carnivorous mammals in

1188-420: The castle's moat shapeshifts into a woman, invites males, and then kills and eats them. Olecranon The olecranon is situated at the proximal end of the ulna, one of the two bones in the forearm . When the hand faces forward ( supination ) the olecranon faces towards the back (posteriorly). It is bent forward at the summit so as to present a prominent lip which is received into the olecranon fossa of

1232-404: The centrum) on the headward side and another on the tailward side, making the centrum appear somewhat like the letter H from the top-view looking down. This tail anatomy is similar to beavers and otters, which use their tails for paddling and propulsion. Fur was preserved on the holotype, and it is the earliest known pelt ; this showed that fur, with its many uses including heat retention and as

1276-650: The cunning wolf. In Japanese, otters are called "kawauso" ( 獺、川獺 ). In Japanese folklore, they fool humans in the same way as foxes ( kitsune ) and tanuki . In the Noto region , Ishikawa Prefecture , there are stories where they shapeshift into beautiful women or children wearing checker-patterned clothing. If a human attempts to speak to one, they will answer "oraya" and then answer "araya," and if anybody asks them anything, they say cryptic things like "kawai." There are darker stories, such as one from Kaga Province (now Ishikawa Prefecture ) in which an otter that lives in

1320-527: The discovery of other unusual mammaliaforms, disproves the previous hypothesis of Mammaliaformes remaining evolutionarily stagnant until the extinction of the non-avian dinosaurs . Weighing an estimated 500–800 g (1.1–1.8 lb), Castorocauda is the largest known Jurassic mammaliaform. It is the earliest known mammaliaform with aquatic adaptations or a fur pelt . It was also adapted for digging, and its teeth are similar to those of seals and Eocene whales, collectively suggesting it behaved similarly to

1364-517: The form of an otter. The myth of "Otter's Ransom" is the starting point of the Volsunga saga . In Irish mythology , the character Lí Ban was turned from a woman into a mermaid, half human and half salmon, and given three hundred years of life to roam the oceans. Her lapdog assumed the form of an otter and shared her prolonged lifetime and her extensive wanderings. In some Native American cultures, otters are considered totem animals . The otter

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1408-677: The fur of otters. Otters have also been hunted using dogs, especially the otterhound . From 1958 to 1963, the 11 otter hunts in England and Wales killed 1,065 otters between them. In such hunts, the hunters notched their poles after every kill. The prized trophy that hunters would take from the otters was the baculum , which would be worn as a tie-pin . Traffic (the wildlife trade monitoring network) reported that otters are at serious risk in Southeast Asia and have disappeared from parts of their former range. This decline in populations

1452-408: The margin, by a slight transverse groove for the attachment of part of the posterior ligament of the elbow-joint. Its anterior surface is smooth, concave, and forms the upper part of the semilunar notch . Its borders present continuations of the groove on the margin of the superior surface; they serve for the attachment of ligaments, viz., the back part of the ulnar collateral ligament medially, and

1496-472: The modern-day platypus and river otters and ate primarily fish. It lived in a wet, seasonal, cool temperate environment – which possibly had an average temperature not exceeding 15 °C (59 °F) – alongside salamanders, pterosaurs, birdlike dinosaurs, and other mammaliaforms. The holotype specimen , JZMP 04117, was discovered in the Daohugou Beds of the Jiulongshan Formation in

1540-410: The platypus. There are traces of soft tissue between the toes, suggesting webbed hind feet. It likely also had claws , and the holotype shows a spur on the hind ankle, which, in male platypuses, is venomous. Castorocauda likely had 14 thoracic , 7 lumbar , 3 sacral and 25 tail vertebrae. Like some mammals, it had plated ribs, and the ribs extended into the lumbar vertebrae. Plating occurred on

1584-522: The posterior ligament laterally. From the medial border a part of the flexor carpi ulnaris arises; while to the lateral border the anconeus muscle is attached. Fractures of the olecranon are common injuries. An olecranon fracture with anterior displacement of the radial head is called a Hume fracture . The word "olecranon" comes from the Greek olene, meaning elbow, and kranon, meaning head. [REDACTED] This article incorporates text in

1628-400: The powerful webbed feet used to swim, and their seal-like abilities for holding breath underwater. Most have sharp claws on their feet and all except the sea otter have long, muscular tails. The 13 species range in adult size from 0.6 to 1.8 m (2.0 to 5.9 ft) in length and 1 to 45 kg (2.2 to 99.2 lb) in weight. The Asian small-clawed otter is the smallest otter species and

1672-661: The proximal margins (the part of the rib closest to the vertebra), and, in Castorocauda , they may have served to increase the insertion area (the part of a muscle which moves while contracting ) of the iliocostalis muscle on the back, which would interlock nearby ribs and better support the torso of the animal. Plated ribs are present in arboreal (tree-dwelling) and fossorial (burrowing) xenarthrans ( sloths , anteaters , armadillos and relatives). The tail vertebrae are flattened dorsoventrally (shortened vertically and widened more horizontally); and each centrum has two pairs of transverse processes (which jut out diagonally from

1716-400: The smell of which has been described as ranging from freshly mown hay to putrefied fish; these are known as spraints . The gestation period in otters is about 60 to 86 days. The newborn pup is cared for by the bitch, dog, and older offspring. Female otters reach sexual maturity at approximately two years of age and males at approximately three years. The holt is built under tree roots or

1760-415: The species. Otters are distinguished by their long, slim bodies, powerful webbed feet for swimming, and their dense fur, which keeps them warm and buoyant in water. They are playful animals, engaging in activities like sliding into water on natural slides and playing with stones. There are 13 known species of otters, ranging in size and habitat preferences, with some species adapted to cold waters requiring

1804-727: The temperature. In water as warm as 10 °C (50 °F), an otter needs to catch 100 g (3.5 oz) of fish per hour to survive. Most species hunt for three to five hours each day and nursing mothers up to eight hours each day. For most otters, fish is the staple of their diet. This is often supplemented by frogs, crayfish and crabs . Some otters are experts at opening shellfish , and others will feed on available small mammals or birds. Prey-dependence leaves otters very vulnerable to prey depletion. Sea otters are hunters of clams , sea urchins and other shelled creatures. They are notable for their ability to use stones to break open shellfish on their bellies. This skill must be learned by

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1848-1008: The water. They may also find and play with small stones. Different species vary in their social structure, some being largely solitary, while others live in groups – in a few species these groups may be fairly large. Giant otter ( Pteronura brasiliensis ) North American river otter ( Lontra canadensis ) Marine otter ( Lontra felina ) Southern river otter ( Lontra provocax ) Neotropical otter ( Lontra longicaudis ) Sea otter ( Enhydra lutris ) Spotted-necked otter ( Hydrictis maculicollis ) Eurasian otter ( Lutra lutra ) Hairy-nosed otter ( Lutra sumatrana ) Japanese otter † ( Lutra nippon ) Lutra euxena † Lutra castiglionis † Lutra simplicidens † Lutra trinacriae † African clawless otter ( Aonyx capensis ) Asian small-clawed otter ( Aonyx cinerea ) Congo clawless otter ( Aonyx congicus ) Smooth-coated otter ( Lutrogale perspicillata ) Subfamily Lutrinae Otters have been hunted for their pelts from at least

1892-529: The young. Otters are active hunters, chasing prey in the water or searching the beds of rivers, lakes or the seas. Most species live beside water, but river otters usually enter it only to hunt or travel, otherwise spending much of their time on land to prevent their fur becoming waterlogged. Sea otters are considerably more aquatic and live in the ocean for most of their lives. Otters are playful animals and appear to engage in various behaviors for sheer enjoyment, such as making waterslides and sliding on them into

1936-614: Was the largest of known docodonts. The preserved length from head to tail is 425 mm (16.7 in), but in life it was much larger. Based on the dimensions of the platypus, the lower weight limit was estimated to be 518 g (1.1 lb) in life, and the upper 700 to 800 g (1.5 to 1.8 lb), making it the largest known Jurassic mammaliaform, surpassing the previous record of 500 g (1.1 lb) for Sinoconodon . It had specialized teeth that curve backwards to help it hold onto slippery fish, as seen in modern seals and also ancestral whales. The first two molars have cusps in

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