Marine vertebrate

Marine vertebrates are vertebrates that live in marine environments. These are the marine fish and the marine tetrapods (primarily seabirds, marine reptiles, and marine mammals). Vertebrates are a subphylum of chordates that have a vertebral column (backbone). The vertebral column provides the central support structure for an internal skeleton. The internal skeleton gives shape, support, and protection to the body and can provide a means of anchoring fins or limbs to the body. The vertebral column also serves to house and protect the spinal cord that that lies within the column.

Marine vertebrates can be divided into two groups, marine fish and marine tetrapods.

SpermWhaleLyd3
Marine tetrapod (sperm whale)

Marine fish

Fish fall into two main groups: fish with bony internal skeletons and fish with cartilaginous internal skeletons. Fish anatomy and physiology generally includes a two-chambered heart, eyes adapted to seeing underwater, and a skin protected by scales and mucous. They typically breathe by extracting oxygen from water through gills. Fish use fins to propel and stabilise themselves in the water. Over 33,000 species of fish have been described as of 2017,[1] of which about 20,000 are marine fish.[2]

Jawless fish

Hagfish form a class of about 20 species of eel-shaped, slime-producing marine fish. They are the only known living animals that have a skull but no vertebral column. Lampreys form a superclass containing 38 known extant species of jawless fish.[3] The adult lamprey is characterized by a toothed, funnel-like sucking mouth. Although they are well known for boring into the flesh of other fish to suck their blood,[4] only 18 species of lampreys are actually parasitic.[5] Together hagfish and lampreys are the sister group to vertebrates. Living hagfish remain similar to hagfish from around 300 million years ago.[6] The lampreys are a very ancient lineage of vertebrates, though their exact relationship to hagfishes and jawed vertebrates is still a matter of dispute.[7] Molecular analysis since 1992 has suggested that hagfish are most closely related to lampreys,[8] and so also are vertebrates in a monophyletic sense. Others consider them a sister group of vertebrates in the common taxon of craniata.[9]

Eptatretus polytrema

Hagfish are the only known living animals with a skull but no vertebral column.

Eudontomyzon mariae Dunai ingola

Lampreys are often parasitic and have a toothed, funnel-like sucking mouth

Pteraspidomorphi

The extinct Pteraspidomorphi, ancestral to jawed vertebrates

Pteraspidomorphi is an extinct class of early jawless fish ancestral to jawed vertebrates. The few characteristics they share with the latter are now considered as primitive for all vertebrates.

Cartilaginous fish

Cartilaginous fish, such as sharks and rays, have jaws and skeletons made of cartilage rather than bone. Megalodon is an extinct species of shark that lived about 28 to 1.5 Ma. It looked much like a stocky version of the great white shark, but was much larger with fossil lengths reaching 20.3 metres (67 ft).[10] Found in all oceans[11] it was one of the largest and most powerful predators in vertebrate history,[10] and probably had a profound impact on marine life.[12] The Greenland shark has the longest known lifespan of all vertebrates, about 400 years.[13]

Acanthodes BW spaced

Cartilaginous fishes may have evolved from spiny sharks

Manta ray - Chura-umi Aquarium

The manta ray, largest ray in the world, has been targeted by fisheries and is now vulnerable.[14]

Pristis clavata 2

Sawfish are rays with long rostrums resembling a saw. All are now endangered or critically endangered[15]

Carcharodon megalodon size compasison with man

The extinct megalodon resembled a giant great white shark

Somniosus microcephalus1

The Greenland shark lives longer than any other vertebrate

Rhincodon typus (recropped)

The largest extant fish, the whale shark, is now a vulnerable species

Bony fish

Bony fish have jaws and skeletons made of bone rather than cartilage. About 90% of the world's fish species are bony fish. Bony fish also have hard, bony plates called operculum which help them respire and protect their gills, and they often possess a swim bladder which they use for better control of their buoyancy.

Bony fish can be further divided into those with lobe fins and those with ray fins. Lobe fins have the form of fleshy lobes supported by bony stalks which extend from the body.[16] Lobe fins evolved into the legs of the first tetrapod land vertebrates, so by extension an early ancestor of humans was a lobe-finned fish. Apart from the coelacanths and the lungfishes, lobe-finned fishes are now extinct. The rest of the modern fish have ray fins. These are made of webs of skin supported by bony or horny spines (rays) which can be erected to control the fin stiffness.

Anguilla japonica 1856

Eel

Marine tetrapods

Tiktaalik BW flopped
Some lobe-finned fishes, like the extinct Tiktaalik, developed limb-like fins that could take them onto land

A tetrapod (Greek for four feet) is a vertebrate with limbs (feet). Tetrapods evolved from ancient lobe-finned fishes about 400 million years ago during the Devonian Period when their earliest ancestors emerged from the sea and adapted to living on land.[17] This change from a body plan for breathing and navigating in gravity-neutral water to a body plan with mechanisms enabling the animal to breath in air without dehydrating and move on land is one of the most profound evolutionary changes known.[18][19] Tetrapods can be divided into four classes: amphibians, reptiles, birds and mammals.

Marine tetrapods are tetrapods that returned from land back to the sea again. The first returns to the ocean may have occurred as early as the Carboniferous Period[20] whereas other returns occurred as recently as the Cenozoic, as in cetaceans, pinnipeds,[21] and several modern amphibians.[22]

Amphibians

Amphibians (Greek for both kinds of life) live part of their life in water and part on land. They mostly require fresh water to reproduce. A few inhabit brackish water, but there are no true marine amphibians.[23] There have been reports, however, of amphibians invading marine waters, such as a Black Sea invasion by the natural hybrid Pelophylax esculentus reported in 2010.[24]

Reptiles

Reptiles (Late Latin for creeping or crawling) do not have an aquatic larval stage, and in this way are unlike amphibians. Most reptiles are oviparous, although several species of squamates are viviparous, as were some extinct aquatic clades[25] — the fetus develops within the mother, contained in a placenta rather than an eggshell. As amniotes, reptile eggs are surrounded by membranes for protection and transport, which adapt them to reproduction on dry land. Many of the viviparous species feed their fetuses through various forms of placenta analogous to those of mammals, with some providing initial care for their hatchlings.

Some reptiles are more closely related to birds than other reptiles, and many scientists prefer to make Reptilia a monophyletic group which includes the birds.[26][27][28][29] Extant non-avian reptiles which inhabit or frequent the sea include sea turtles, sea snakes, terrapins, the marine iguana, and the saltwater crocodile. Currently, of the approximately 12,000 extant reptile species and sub-species, only about 100 of are classed as marine reptiles.[30]

Except for some sea snakes, most extant marine reptiles are oviparous and need to return to land to lay their eggs. Apart from sea turtles, the species usually spend most of their lives on or near land rather than in the ocean. Sea snakes generally prefer shallow waters nearby land, around islands, especially waters that are somewhat sheltered, as well as near estuaries.[31][32] Unlike land snakes, sea snakes have evolved flattened tails which help them swim.[33]

Micrurus fulviusHolbrookV3P10AA

Marine snakes have flattened tails

Ichthyosaurus BW

The ancient Ichthyosaurus communis independently evolved flippers similar to dolphins

Some extinct marine reptiles, such as ichthyosaurs, evolved to be viviparous and had no requirement to return to land. Ichthyosaurs resembled dolphins. They first appeared about 245 million years ago and disappeared about 90 million years ago. The terrestrial ancestor of the ichthyosaur had no features already on its back or tail that might have helped along the evolutionary process. Yet the ichthyosaur developed a dorsal and tail fin which improved its ability to swim.[34] The biologist Stephen Jay Gould said the ichthyosaur was his favourite example of convergent evolution.[35] The earliest marine reptiles arose in the Permian. During the Mesozoic many groups of reptiles became adapted to life in the seas, including ichthyosaurs, plesiosaurs, mosasaurs, nothosaurs, placodonts, sea turtles, thalattosaurs and thalattosuchians. Marine reptiles were less numerous after mass extinction at the end of the Cretaceous.

Birds

Marine birds are adapted to life within the marine environment. They are often called seabirds. While marine birds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations. Examples include albatross, penguins, gannets, and auks.

In general, marine birds live longer, breed later and have fewer young than terrestrial birds do, but they invest a great deal of time in their young. Most species nest in colonies, which can vary in size from a few dozen birds to millions. Many species are famous for undertaking long annual migrations, crossing the equator or circumnavigating the Earth in some cases. They feed both at the ocean's surface and below it, and even feed on each other. Marine birds can be highly pelagic, coastal, or in some cases spend a part of the year away from the sea entirely. Some marine birds plummet from heights, plunging through the water leaving vapour-like trails, similar to that of fighter planes.[36] Gannets plunge into the water at up to 100 kilometres per hour (60 mph). They have air sacs under their skin in their face and chest which act like bubble-wrap, cushioning the impact with the water.

Goéland argenté - Julien Salmon

European herring gull attack herring schools from above

Pygoscelis papua -Nagasaki Penguin Aquarium -swimming underwater-8a

Gentoo penguin swimming underwater

Morus serrator

Gannets "divebomb" at high speed

Diomedea exulans in flight - SE Tasmania

Albatrosses range over huge areas of ocean and regularly circle the globe.

The first marine birds evolved in the Cretaceous period, and modern marine bird families emerged in the Paleogene.

Mammals

Sea otter with sea urchin
Sea otter, classic keystone species which controls sea urchin numbers

Mammals (from Latin for breast) are characterised by the presence of mammary glands which in females produce milk for feeding (nursing) their young. There are about 130 living and recently extinct marine mammal species such as seals, dolphins, whales, manatees, sea otters and polar bears.[37] They do not represent a distinct taxon or systematic grouping, but are instead unified by their reliance on the marine environment for feeding. Both cetaceans and sirenians are fully aquatic and therefore are obligate water dwellers. Seals and sea-lions are semiaquatic; they spend the majority of their time in the water, but need to return to land for important activities such as mating, breeding and molting. In contrast, both otters and the polar bear are much less adapted to aquatic living. Their diet varies considerably as well: some may eat zooplankton; others may eat fish, squid, shellfish, and sea-grass; and a few may eat other mammals.

In a process of convergent evolution, marine mammals such as dolphins and whales redeveloped their body plan to parallel the streamlined fusiform body plan of pelagic fish. Front legs became flippers and back legs disappeared, a dorsal fin reappeared and the tail morphed into a powerful horizontal fluke. This body plan is an adaptation to being an active predator in a high drag environment. A parallel convergence occurred with the now extinct ichthyosaur.[38]

Bluewhale2 noaa

Endangered blue whale, largest animal ever[39]

Tursiops truncatus 01

Bottlenose dolphin, highest encephalization of any animal after humans[40]

Dugong Marsa Alam

Dugong grazing on seagrass

See also

References

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Balaenoptera

Balaenoptera, from the Latin balaena (whale) and Ancient Greek pteron (fin), is a genus of Balaenopteridae, the rorquals, and contains eight extant species. The species Balaenoptera omurai was published in 2003. Balaenoptera is a diverse genus and comprises all but one of the extant species in its family - the other species is the humpback whale, Megaptera novaeangliae.

This genus is known in the fossil records from the Neogene to the Quaternary (age range: from 13.65 to 0.0 million years ago).

Bentiaba River

The Bentiaba (or Rio de São Nicolau or Saint Nicolas River) is a river in southern Angola. Its mouth is at the Atlantic Ocean near the commune of Bentiaba in Namibe Province.

The riverbank has produced a number of Cretaceous fossils including mosasaurs.

Bentiaba is also the name given to the Cretaceous bonebed.

Bone bed

A bone bed is any geological stratum or deposit that contains bones of whatever kind. Inevitably, such deposits are sedimentary in nature. Not a formal term, it tends to be used more to describe especially dense collections such as Lagerstätte. It is also applied to brecciated and stalagmitic deposits on the floor of caves, which frequently contain osseous remains.In a more restricted sense, the term is used to describe certain thin layers of bony fragments, which occur in well-defined geological strata. One of the best-known of these is the Ludlow Bone Bed, which is found at the base of the Downton Sandstone in the Upper Ludlow series. At Ludlow (England) itself, two such beds are actually known, separated by about 14 ft (4.3 m). of strata. Although quite thin, the Ludlow Bone Bed can be followed from that town into Gloucestershire, for a distance of 45 miles (72 km). It is almost completely made up of fragments of spines, teeth and scales of ganoid fish. Another well-known bed, formerly known as the Bristol or Lias Bone Bed, exists in the form of several thin layers of micaceous sandstone, with the remains of fish and saurians, which occur in the Rhaetic Black Paper Shales that lie above the Keuper marls, in the south-west of England. It is noteworthy that a similar bone bed has been traced on the same geological horizon in Brunswick, Hanover (Germany), in Franconia and in Tübingen (Germany). A bone bed has also been observed at the base of the Carboniferous limestone series, in certain parts of the south-west of England.Bone beds are also recorded in North America, South America, Mongolia and China. Terrestrial bonebed examples are: the Triassic Metoposaurus bone bed from Portugal, the Mapusaurus bone bed at Cañadón del Gato, in Argentina, the Allosaurus-dominated Cleveland-Lloyd Dinosaur Quarry of Utah, the Dinosaur National Monument on the boundary of Utah and Colorado, an Albertosaurus bone bed from Alberta, a Daspletosaurus bone bed from Montana, the Cenozoic John Day Fossil Beds of Oregon and the Nemegt Basin in the Gobi Desert region of Mongolia. Bentiaba, Angola, is an example of a marine bonebed with numerous mosasaurs and plesiosaurs.

Bramerton Pits

Bramerton Pits is a 0.7-hectare (1.7-acre) geological Site of Special Scientific Interest north of the village of Bramerton in Norfolk on the southern banks of the River Yare. It is a Geological Conservation Review site.The site is composed of two disused gravel pits which are important for the study of the Lower Pleistocene. Bramerton Common Pit is the type site of the Norwich Crag Formation and Blakes Pit is the type site of the Bramertonian Stage. Both pits have yielded rich, mainly marine vertebrate fossils.The geological deposits include sands, silts and gravels which have yielded fossils of marine and non-marine mollusca, foraminifera and vertebrates. Studies of fossils from Blake’s Pit have demonstrated changes from temperate (Bramertonian) to cold (Pre-Pastonian) climatic conditions. Bramerton Common Pit has yielded a rich fossil vertebrate fauna including marine fishes and extinct species of gomphothere mastodont, otter and vole. Both sites are nationally important for understanding early Pleistocene environments and faunal changes in Britain.

Bramerton Common Pit is adjacent to Bramerton Common near Woods End and Blakes Pit is further east at the end of Hill House Road. There is public access to the site.

Digital Fish Library

The Digital Fish Library (DFL) is a University of California San Diego project funded by the Biological Infrastructure Initiative (DBI) of the National Science Foundation (NSF). The DFL creates 2D and 3D visualizations of the internal and external anatomy of fish obtained with magnetic resonance imaging (MRI) methods and makes these publicly available over the web.

The information core for the Digital Fish Library is generated using high-resolution MRI scanners housed at the Center for Functional Magnetic Resonance Imaging (CfMRI) multi-user facility at UC San Diego. These instruments use magnetic fields to take 3D images of animal tissues, allowing researchers to non-invasively see inside them and quantitatively describe their 3D anatomy. Fish specimens are obtained from the Marine Vertebrate Collection at Scripps Institute of Oceanography (SIO) and imaged by staff from UC San Diego's Center for Scientific Computation in Imaging (CSCI).

As of February 2010, the Digital Fish Library contains almost 300 species covering all five classes of fish, 56 of 60 orders, and close to 200 of the 521 fish families as described by Nelson, 2006. DFL imaging has also contributed to a number of published peer-reviewed scientific studies.

Digital Fish Library work has been featured in the media including two National Geographic documentaries: Magnetic Navigator and Ultimate Shark.

George C. Williams (biologist)

George Christopher Williams (May 12, 1926 – September 8, 2010) was an American evolutionary biologist.Williams was a professor of biology at the State University of New York at Stony Brook who was best known for his vigorous critique of group selection. The work of Williams in this area, along with W. D. Hamilton, John Maynard Smith and others led to the development of a gene-centric view of evolution in the 1960s.

Kent E. Carpenter

Dr. Kent E. Carpenter is a professor of biological sciences at Old Dominion University, in Norfolk, Virginia, who is notable for having two fish species named in his honor, Paracheilinus carpenteri Randall and Lubbock 1981, popularly known as "Carpenter's flasher wrasse", and Meganthias carpenteri Anderson 2006, popularly known as Carpenter's Yellowtop Jewelfish.Dr. Carpenter earned his Bachelor of Science degree in marine biology at Florida Institute of Technology in 1975 and his Doctor of Philosophy degree in zoology at the University of Hawaii. His research emphasis is in the systematics and evolution of marine fishes. His work in marine biogeography for the Indian Ocean and west Pacific Ocean has led to work in marine conservation and comparative phylogeography using population genetics, with a special interest in the Philippines.

He is also a long-term collaborator with the Food and Agriculture Organization of the United Nations Species Identification and Data Programme for Fisheries, producing identification guides for regions such as the western Pacific and the western and eastern Atlantic Oceans. He has done fieldwork in the Caribbean, West Africa, and the Philippines. In addition to research and teaching responsibilities, he is also the coordinator for the IUCN Global Marine Species Assessment, completing the first global review of every marine vertebrate species, and of selected marine invertebrates and marine plants, to determine conservation status and possible extinction risk for about 20,000 marine species.

Kitadani Formation

The Kitadani Formation is a unit of Lower Cretaceous sedimentary rock which crops out near the city of Katsuyama in the Fukui Prefecture of Japan, and it is the primary source of Cretaceous-aged non-marine vertebrate fossils in Japan. Dinosaur remains are among the fossils that have been recovered from the formation, but it also preserves a diverse assemblage of plants, invertebrates, and other vertebrates. Most, if not all, of the fossil specimens collected from the Kitadani Formation are reposited at the Fukui Prefectural Dinosaur Museum.The Kitadani Formation is a unit within the Akaiwa Subgroup of the Tetori Group, a major sequence of Mesozoic-aged rocks which is distributed across the Fukui, Ishikawa, and Gifu prefectures of western-central Honshu, Japan. The Tetori Group exhibits marked lateral variation, and the Kitadani Formation is only present in the Fukui Prefecture. The Kitadani Formation comprises interbedded tuffs, sandstones, and shales and reaches a maximum thickness of approximately 100 m (~328 feet). It conformably overlies the Akaiwa Formation and is unconformably overlain by the Omichidani Formation. The Kitadani Formation is significant because it is the major source of dinosaur fossils in Japan and because of Japan's unique position along the northeastern margin of Eurasia during the Early Cretaceous.

List of National Natural Landmarks in California

From List of National Natural Landmarks, these are the National Natural Landmarks in California. There are 36 in total.

Megaptera miocaena

"Megaptera" miocaena is an extinct species of Balaenopteridae from the late Miocene of California. It was originally considered a species of Megaptera, but is no longer seen as congeneric with the humpback whale and thus in need of a new generic name.

Osedax

Osedax is a genus of deep-sea siboglinid polychaetes, commonly called boneworms, zombie worms, or bone-eating worms. Osedax is Latin for "bone-eating". The name alludes to how the worms bore into the bones of whale carcasses to reach enclosed lipids, on which they rely for sustenance.

Scientists from the Monterey Bay Aquarium Research Institute using the submarine ROV Tiburon first discovered the genus in Monterey Bay, California, in February 2002. The worms were found living on the bones of a decaying gray whale in the Monterey Canyon, at a depth of 2,893 m (9,491 ft).

Ouled Abdoun Basin

The Oulad Abdoun Basin (also known as the Ouled Abdoun Basin or Khouribga Basin) is a phosphate sedimentary basin located in Morocco, near the city of Khouribga. It is the largest in Morocco, comprising 44% of Morocco's phosphate reserves, and at least 26.8 billion tons of phosphate. It is also known as an important site for vertebrate fossils, with deposits ranging from the Late Cretaceous (Cenomanian-Turonian) to the Eocene epoch (Ypresian), a period of about 25 million years.

Paleontology in Missouri

Paleontology in Missouri refers to paleontological research occurring within or conducted by people from the U.S. state of Missouri. The geologic column of Missouri spans all of geologic history from the Precambrian to present with the exception of the Permian, Triassic, and Jurassic. Brachiopods are probably the most common fossils in Missouri.During the early Paleozoic, Missouri was covered by a warm shallow sea that would come to be home to creatures like Archimedes, brachiopods, shelled cephalopods, conodonts, corals, crinoids, armored fishes, and trilobites. During the Carboniferous a rich flora developed on land. Primitive tetrapods left behind footprints that would later fossilize. By the end of that period the sea had disappeared from the state. The Permian, Triassic, and Jurassic are missing from the local rock record. At that time southeastern Missouri was covered in seawater. On land, the state was home to dinosaurs. Missouri remained partially covered by seawater into the early Cenozoic while a great diversity of trees grew on land.During the Ice Age the northern part of the state was covered in glaciers while the southern half was home to creatures like camels, mammoths, and mastodons. The state's mastodons are among the most prominent of its Ice Age mammal fauna.The Pennsylvanian sea lily, Delocrinus missouriensis, is the Missouri state fossil. Hypsibema missouriensis is the state dinosaur.

Stony Brook Southampton

Stony Brook Southampton is a campus location of the State University of New York at Stony Brook, located in Southampton, New York between the Shinnecock Indian Reservation and Shinnecock Hills Golf Club on the eastern end of Long Island.

Thermopolis Shale

The Thermopolis Shale is a geologic formation which formed in west-central North America in the Albian age of the Late Cretaceous period. Surface outcroppings occur in central Canada, and the U.S. states of Montana and Wyoming. The rock formation was laid down over about 7 million years by sediment flowing into the Western Interior Seaway. The formation's boundaries and members are not well-defined by geologists, which has led to different definitions of the formation. Some geologists conclude the formation should not have a designation independent of the formations above and below it. A range of invertebrate and small and large vertebrate fossils and coprolites are found in the formation.

Vertebrate

Vertebrates comprise all species of animals within the subphylum Vertebrata (chordates with backbones). Vertebrates represent the overwhelming majority of the phylum Chordata, with currently about 69,276 species described. Vertebrates include such groups as the following:

jawless fishes

jawed vertebrates, which include the cartilaginous fishes (sharks, rays, and ratfish)

tetrapods, which include amphibians, reptiles, birds and mammals

bony fishesExtant vertebrates range in size from the frog species Paedophryne amauensis, at as little as 7.7 mm (0.30 in), to the blue whale, at up to 33 m (108 ft). Vertebrates make up less than five percent of all described animal species; the rest are invertebrates, which lack vertebral columns.

The vertebrates traditionally include the hagfish, which do not have proper vertebrae due to their loss in evolution, though their closest living relatives, the lampreys, do. Hagfish do, however, possess a cranium. For this reason, the vertebrate subphylum is sometimes referred to as "Craniata" when discussing morphology.

Molecular analysis since 1992 has suggested that hagfish are most closely related to lampreys, and so also are vertebrates in a monophyletic sense. Others consider them a sister group of vertebrates in the common taxon of craniata.

Wadi El Hitan

Wadi Al-Hitan, (Arabic: وادي الحيتان‎, "Whale Valley") is a paleontological site in the Faiyum Governorate of Egypt, some 150 km southwest of Cairo. It was designated a UNESCO World Heritage Site in July 2005 for its hundreds of fossils of some of the earliest forms of whale, the archaeoceti (a now extinct sub-order of whales). The site reveals evidence for the explanation of one of the greatest mysteries of the evolution of whales: the emergence of the whale as an ocean-going mammal from a previous life as a land-based animal. No other place in the world yields the number, concentration and quality of such fossils, as is their accessibility and setting in an attractive and protected landscape. This is why it was added by the UNESCO to the list of protected World Heritage sites.The fossils found at the site may not be the oldest but their great concentration in the area and the degree of their preservation is to the extent that even some stomach contents are intact. The presence of fossils of other early animals such as sharks, crocodiles, sawfish, turtles and rays found at Wadi El-Hitan makes it possible to reconstruct the surrounding environmental and ecological conditions of the time, adding to its justification to be cited as a Heritage site.

The first fossil skeletons of whales were discovered in the winter of 1902-3. For the next 80 years they attracted relatively little interest, largely due to the difficulty of reaching the area. In the 1980s interest in the site resumed as four wheel drive vehicles became more readily available. Continuing interest coincided with the site being visited by fossil collectors, and many bones were removed, prompting calls for the site to be conserved. The remains display the typical streamlined body form of modern whales, yet retaining some of the primitive aspects of skull and tooth structure. The largest skeleton found reached up to 21 m in length, with well-developed five-fingered flippers on the forelimbs and the unexpected presence of hind legs, feet, and toes, not known previously in any archaeoceti. Their form was serpentine and they were carnivorous. A few of these skeletal remains are exposed but most are shallowly buried in sediments, slowly uncovered by erosion. Wadi El-Hitan provides evidences of millions of years of coastal marine life.

Whale fall

A whale fall is the carcass of a cetacean that has fallen into the bathyal or abyssal zone (i.e. deeper than 1,000 m, or 3,300 ft) on the ocean floor. They can create complex localized ecosystems that supply sustenance to deep-sea organisms for decades. This is unlike in shallower waters, where a whale carcass will be consumed by scavengers over a relatively short period of time. It was with the development of deep-sea robotic exploration that whale falls were first observed in the late 1970s.Organisms that have been observed at deep-sea whale falls include giant isopods, squat lobsters, bristleworms, prawns, shrimp, lobsters, hagfish, Osedax, crabs, sea cucumbers, and sleeper sharks.

Whale falls are able to occur in the deep open ocean due to cold temperatures and high hydrostatic pressures. In the coastal ocean, a higher incidence of predators as well as warmer waters hasten the decomposition of whale carcasses. Carcasses may also float due to decompositional gases, keeping the carcass at the surface. In the deep-sea, cold temperatures slow decomposition rates, and high hydrostatic pressures increase gas solubility, allowing whale falls to remain intact and sink to great depths.

Yunguisaurus

Yunguisaurus is an extinct genus of pistosaur known from the Guizhou Province of China.

Aquatic ecosystems

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