Marine vertebrate

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Skeleton of a bass.jpg
Ray-finned fish
SpermWhaleLyd3.jpg
Marine tetrapod (sperm whale)
Internal skeletal structures showing the vertebral column running from the head to the tail

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 lies within the column.

Contents

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

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]

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]

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.

Marine tetrapods

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

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.

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

Mammals

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

See also

Related Research Articles

<span class="mw-page-title-main">Chordate</span> Phylum of animals having a dorsal nerve cord

A chordate is a deuterostomic animal belonging to the phylum Chordata. All chordates possess, at some point during their larval or adult stages, five distinctive physical characteristics (synapomorphies) that distinguish them from other taxa. These five synapomorphies are a notochord, a hollow dorsal nerve cord, an endostyle or thyroid, pharyngeal slits, and a post-anal tail. The name "chordate" comes from the first of these synapomorphies, the notochord, which plays a significant role in chordate body plan structuring and movements. Chordates are also bilaterally symmetric, have a coelom, possess a closed circulatory system, and exhibit metameric segmentation.

<span class="mw-page-title-main">Osteichthyes</span> Diverse group of fish with skeletons of bone rather than cartilage

Osteichthyes, commonly referred to as the bony fish, is a diverse superclass of vertebrate animals that have skeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes, which have skeletons primarily composed of cartilage. The vast majority of extant fish are members of Osteichthyes, which is an extremely diverse and abundant group consisting of 45 orders, over 435 families and 28,000 species. It is the largest class of vertebrates in existence today.

The Phanerozoic is the current and the latest of the four geologic eons in the Earth's geologic time scale, covering the time period from 538.8 million years ago to the present. It is the eon during which abundant animal and plant life has proliferated, diversified and colonized various niches on the Earth's surface, beginning with the Cambrian period when animals first developed hard shells that can be clearly preserved in the fossil record. The time before the Phanerozoic, collectively called the Precambrian, is now divided into the Hadean, Archaean and Proterozoic eons.

<span class="mw-page-title-main">Vertebrate</span> Subphylum of chordates with backbones

Vertebrates are deuterostomal animals with bony or cartilaginous axial endoskeleton — known as the vertebral column, spine or backbone — around and along the spinal cord, including all fish, amphibians, reptiles, birds and mammals. The vertebrates consist of all the taxa within the subphylum Vertebrata and represent the overwhelming majority of the phylum Chordata, with currently about 69,963 species described.

<span class="mw-page-title-main">Tetrapod</span> Superclass of the first four-limbed vertebrates and their descendants

A tetrapod is any four-limbed vertebrate animal of the superclass Tetrapoda. Tetrapods include all extant and extinct amphibians and amniotes, with the latter in turn evolving into two major clades, the sauropsids and synapsids. Some tetrapods such as snakes, legless lizards, and caecilians had evolved to become limbless via mutations of the Hox gene, although some do still have a pair of vestigial spurs that are remnants of the hindlimbs.

<span class="mw-page-title-main">Sarcopterygii</span> Class of fishes

Sarcopterygii — sometimes considered synonymous with Crossopterygii — is a taxon of the bony fish known as the lobe-finned fish or sarcopterygians, characterised by prominent muscular limb buds (lobes) within the fins, which are supported by articulated appendicular skeletons. This is in contrast to the other clade of bony fish, the Actinopterygii, which have only skin-covered bony spines (lepidotrichia) supporting the fins.

<span class="mw-page-title-main">Vertebrate paleontology</span> Scientific study of prehistoric vertebrates

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<span class="mw-page-title-main">Ichthyosauria</span> Extinct order of large marine reptiles

Ichthyosauria is an order of large extinct marine reptiles sometimes referred to as "ichthyosaurs," although the term is also used for wider clades that the order resides in.

<span class="mw-page-title-main">Fish anatomy</span> Study of the form or morphology of fishes

Fish anatomy is the study of the form or morphology of fish. It can be contrasted with fish physiology, which is the study of how the component parts of fish function together in the living fish. In practice, fish anatomy and fish physiology complement each other, the former dealing with the structure of a fish, its organs or component parts and how they are put together, such as might be observed on the dissecting table or under the microscope, and the latter dealing with how those components function together in living fish.

<span class="mw-page-title-main">Craniate</span> Clade of chordates, member of the Craniata

A craniate is a member of the Craniata, a proposed clade of chordate animals with a skull of hard bone or cartilage. Living representatives are the Myxini (hagfishes), Hyperoartia, and the much more numerous Gnathostomata. Formerly distinct from vertebrates by excluding hagfish, molecular and anatomical research in the 21st century has led to the reinclusion of hagfish as vertebrates, making living craniates synonymous with living vertebrates.

<span class="mw-page-title-main">Euteleostomi</span> Clade including most vertebrates

Euteleostomi is a successful clade that includes more than 90% of the living species of vertebrates. Both its major subgroups are successful today: Actinopterygii includes most extant bony fish species, and Sarcopterygii includes the tetrapods.

<span class="mw-page-title-main">Flipper (anatomy)</span> Flattened limb adapted for propulsion and maneuvering in water

A flipper is a broad, flattened limb adapted for aquatic locomotion. It refers to the fully webbed, swimming appendages of aquatic vertebrates that are not fish.

<span class="mw-page-title-main">Marine life</span> Organisms that live in salt water

Marine life, sea life, or ocean life is the plants, animals, and other organisms that live in the salt water of seas or oceans, or the brackish water of coastal estuaries. At a fundamental level, marine life affects the nature of the planet. Marine organisms, mostly microorganisms, produce oxygen and sequester carbon. Marine life, in part, shape and protect shorelines, and some marine organisms even help create new land.

Many vertebrates are limbless, limb-reduced, or apodous, with a body plan consisting of a head and vertebral column, but no adjoining limbs such as legs or fins. Jawless fish are limbless but may have preceded the evolution of vertebrate limbs, whereas numerous reptile and amphibian lineages – and some eels and eel-like fish – independently lost their limbs. Larval amphibians, tadpoles, are also often limbless. No mammals or birds are limbless, but some feature partial limb-loss or limb reduction.

<span class="mw-page-title-main">Fish</span> Gill-bearing non-tetrapod aquatic vertebrates

A fish is an aquatic, craniate, gill-bearing animal that lacks limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of living fish species are ray-finned fish, belonging to the class Actinopterygii, with around 99% of those being teleosts.

<span class="mw-page-title-main">Diversity of fish</span> Fish species categorized by various characteristics

Fish are very diverse animals and can be categorised in many ways. Although most fish species have probably been discovered and described, about 250 new ones are still discovered every year. According to FishBase about 34,800 species of fish had been described as of February 2022, which is more than the combined total of all other vertebrate species: mammals, amphibians, reptiles and birds.

<span class="mw-page-title-main">Fish fin</span> Bony skin-covered spines or rays protruding from the body of a fish

Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the spine and are supported only by muscles.

<span class="mw-page-title-main">Evolution of fish</span> Origin and diversification of fish through geologic time

The evolution of fish began about 530 million years ago during the Cambrian explosion. It was during this time that the early chordates developed the skull and the vertebral column, leading to the first craniates and vertebrates. The first fish lineages belong to the Agnatha, or jawless fish. Early examples include Haikouichthys. During the late Cambrian, eel-like jawless fish called the conodonts, and small mostly armoured fish known as ostracoderms, first appeared. Most jawless fish are now extinct; but the extant lampreys may approximate ancient pre-jawed fish. Lampreys belong to the Cyclostomata, which includes the extant hagfish, and this group may have split early on from other agnathans.

<span class="mw-page-title-main">Fish gill</span> Organ that allows fish to breathe underwater

Fish gills are organs that allow fish to breathe underwater. Most fish exchange gases like oxygen and carbon dioxide using gills that are protected under gill covers (operculum) on both sides of the pharynx (throat). Gills are tissues that are like short threads, protein structures called filaments. These filaments have many functions including the transfer of ions and water, as well as the exchange of oxygen, carbon dioxide, acids and ammonia. Each filament contains a capillary network that provides a large surface area for exchanging oxygen and carbon dioxide.

<span class="mw-page-title-main">Evolution of tetrapods</span> Evolution of four legged vertebrates and their derivatives

The evolution of tetrapods began about 400 million years ago in the Devonian Period with the earliest tetrapods evolved from lobe-finned fishes. Tetrapods are categorized as animals in the biological superclass Tetrapoda, which includes all living and extinct amphibians, reptiles, birds, and mammals. While most species today are terrestrial, little evidence supports the idea that any of the earliest tetrapods could move about on land, as their limbs could not have held their midsections off the ground and the known trackways do not indicate they dragged their bellies around. Presumably, the tracks were made by animals walking along the bottoms of shallow bodies of water. The specific aquatic ancestors of the tetrapods, and the process by which land colonization occurred, remain unclear. They are areas of active research and debate among palaeontologists at present.

References

  1. ↑ "FishBase: A Global Information System on Fishes". FishBase . Retrieved 17 January 2017.
  2. ↑ "How Many Fish In The Sea? Census Of Marine Life Launches First Report". Science Daily. Retrieved 17 January 2017.
  3. ↑ Docker, Margaret F. (2006). "Bill Beamish's Contributions to Lamprey Research and Recent Advances in the Field". Guelph Ichthyology Reviews. 7. doi:10.1111/j.1095-8649.2006.00968.x (inactive 31 January 2024).{{cite journal}}: CS1 maint: DOI inactive as of January 2024 (link)
  4. ↑ Hardisty, M. W.; Potter, I. C. (1971). Hardisty, M. W.; Potter, I. C. (eds.). The Biology of Lampreys (1st ed.). Academic Press. ISBN   978-0-123-24801-5.
  5. ↑ Gill, Howard S.; Renaud, Claude B.; Chapleau, François; Mayden, Richard L.; Potter, Ian C.; Douglas, M. E. (2003). "Phylogeny of Living Parasitic Lampreys (Petromyzontiformes) Based on Morphological Data". Copeia. 2003 (4): 687–703. doi:10.1643/IA02-085.1. S2CID   85969032.
  6. ↑ "Myxini". University of California Museum of Paleontology. Archived from the original on 15 December 2017. Retrieved 17 January 2017.
  7. ↑ Greena, Stephen A.; Bronner, Marianne E. (2014). "The Lamprey: A jawless vertebrate model system for examining origin of the neural crest and other vertebrate traits". Differentiation. 87 (1–2): 44–51. doi:10.1016/j.diff.2014.02.001. PMC   3995830 . PMID   24560767.
  8. ↑ Stock, D.; Whitt, G.S. (7 August 1992). "Evidence from 18S ribosomal RNA sequences that lampreys and hagfish form a natural group". Science. 257 (5071): 787–9. Bibcode:1992Sci...257..787S. doi:10.1126/science.1496398. PMID   1496398.
  9. ↑ Nicholls, H. (10 September 2009). "Mouth to Mouth". Nature. 461 (7261): 164–166. doi: 10.1038/461164a . PMID   19741680. S2CID   35838285.
  10. 1 2 Wroe, S.; Huber, D. R.; Lowry, M.; McHenry, C.; Moreno, K.; Clausen, P.; Ferrara, T. L.; Cunningham, E.; Dean, M. N.; Summers, A. P. (2008). "Three-dimensional computer analysis of white shark jaw mechanics: how hard can a great white bite?" (PDF). Journal of Zoology. 276 (4): 336–342. doi:10.1111/j.1469-7998.2008.00494.x.
  11. ↑ Pimiento, Catalina; Dana J. Ehret; Bruce J. MacFadden; Gordon Hubbell (10 May 2010). Stepanova, Anna (ed.). "Ancient Nursery Area for the Extinct Giant Shark Megalodon from the Miocene of Panama". PLOS ONE. 5 (5): e10552. Bibcode:2010PLoSO...510552P. doi: 10.1371/journal.pone.0010552 . PMC   2866656 . PMID   20479893.
  12. ↑ Lambert, Olivier; Bianucci, Giovanni; Post, Klaas; de Muizon, Christian; Salas-Gismondi, Rodolfo; Urbina, Mario; Reumer, Jelle (1 July 2010). "The giant bite of a new raptorial sperm whale from the Miocene epoch of Peru". Nature. 466 (7302): 105–108. Bibcode:2010Natur.466..105L. doi:10.1038/nature09067. PMID   20596020. S2CID   4369352.
  13. ↑ Nielsen, Julius; Hedeholm, Rasmus B.; Heinemeier, Jan; Bushnell, Peter G.; Christiansen, Jørgen S.; Olsen, Jesper; Ramsey, Christopher Bronk; Brill, Richard W.; Simon, Malene; Steffensen, Kirstine F.; Steffensen, John F. (2016). "Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus)". Science. 353 (6300): 702–4. Bibcode:2016Sci...353..702N. doi:10.1126/science.aaf1703. hdl: 2022/26597 . PMID   27516602. S2CID   206647043.
  14. ↑ Marshall, A.; Bennett, M.B.; Kodja, G.; Hinojosa-Alvarez, S.; Galvan-Magana, F.; Harding, M.; Stevens, G. & Kashiwagi, T. (2011). "Manta birostris". IUCN Red List of Threatened Species . 2011: e.T198921A9108067. doi: 10.2305/IUCN.UK.2011-2.RLTS.T198921A9108067.en .
  15. ↑ Black, Richard (11 June 2007). "Sawfish protection acquires teeth". BBC News.
  16. ↑ Clack, J. A. (2002) Gaining Ground. Indiana University
  17. ↑ Narkiewicz, Katarzyna; Narkiewicz, Marek (January 2015). "The age of the oldest tetrapod tracks from Zachełmie, Poland". Lethaia. 48 (1): 10–12. doi:10.1111/let.12083. ISSN   0024-1164.
  18. ↑ Long JA, Gordon MS (September–October 2004). "The greatest step in vertebrate history: a paleobiological review of the fish-tetrapod transition". Physiol. Biochem. Zool. 77 (5): 700–19. doi:10.1086/425183. PMID   15547790. S2CID   1260442. as PDF
  19. ↑ Shubin, N. (2008). Your Inner Fish: A Journey Into the 3.5-Billion-Year History of the Human Body . New York: Pantheon Books. ISBN   978-0-375-42447-2.
  20. ↑ Laurin, M. (2010). How Vertebrates Left the Water. Berkeley, California, USA.: University of California Press. ISBN   978-0-520-26647-6.
  21. ↑ Canoville, Aurore; Laurin, Michel (2010). "Evolution of humeral microanatomy and lifestyle in amniotes, and some comments on paleobiological inferences". Biological Journal of the Linnean Society. 100 (2): 384–406. doi: 10.1111/j.1095-8312.2010.01431.x .
  22. ↑ Laurin, Michel; Canoville, Aurore; Quilhac, Alexandra (2009). "Use of paleontological and molecular data in supertrees for comparative studies: the example of lissamphibian femoral microanatomy". Journal of Anatomy. 215 (2): 110–123. doi:10.1111/j.1469-7580.2009.01104.x. PMC   2740958 . PMID   19508493.
  23. ↑ Hopkins Gareth R.; Brodie Edmund D. Jr (2015). "Occurrence of Amphibians in Saline Habitats: A Review and Evolutionary Perspective". Herpetological Monographs. 29 (1): 1–27. doi:10.1655/HERPMONOGRAPHS-D-14-00006. S2CID   83659304.
  24. ↑ Natchev, N.; Tzankov, N.; Gemel, Richard (2011). "Green frog invasion in the Black Sea: habitat ecology of the Pelophylax esculentus complex (Anura, Amphibia) population in the region of Shablenska Тuzla lagoon in Bulgaria". Herpetology Notes. S2CID   88846435.
  25. ↑ Sander, P. Martin (2012). "Reproduction in early amniotes". Science. 337 (6096): 806–808. Bibcode:2012Sci...337..806S. doi:10.1126/science.1224301. PMID   22904001. S2CID   7041966.
  26. ↑ Modesto, S.P.; Anderson, J.S. (2004). "The phylogenetic definition of Reptilia". Systematic Biology. 53 (5): 815–821. doi: 10.1080/10635150490503026 . PMID   15545258.
  27. ↑ Gauthier, J.A.; Kluge, A.G.; Rowe, T. (1988). "The early evolution of the Amniota". In Benton, M.J. (ed.). The Phylogeny and Classification of the Tetrapods. Vol. 1. Oxford: Clarendon Press. pp. 103–155. ISBN   978-0-19-857705-8.
  28. ↑ Laurin, M.; Reisz, R. R. (1995). "A reevaluation of early amniote phylogeny". Zoological Journal of the Linnean Society . 113 (2): 165–223. doi:10.1111/j.1096-3642.1995.tb00932.x.
  29. ↑ Modesto, S.P. (1999). "Observations of the structure of the Early Permian reptile Stereosternum tumidum Cope". Palaeontologia Africana. 35: 7–19.
  30. ↑ Rasmussen, Arne Redsted; Murphy, John C.; Ompi, Medy; Gibbons, J. Whitfield; Uetz, Peter (8 November 2011). "Marine Reptiles". PLOS ONE. 6 (11): e27373. Bibcode:2011PLoSO...627373R. doi: 10.1371/journal.pone.0027373 . PMC   3210815 . PMID   22087300.
  31. ↑ Stidworthy J. 1974. Snakes of the World. Grosset & Dunlap Inc. 160 pp. ISBN   0-448-11856-4.
  32. ↑ Sea snakes [ permanent dead link ] at Food and Agriculture Organization of the United Nations. Accessed 7 August 2007.
  33. ↑ Rasmussen, A.R.; Murphy, J.C.; Ompi, M.; Gibbons, J.W.; Uetz, P. (2011). "Marine reptiles". PLOS ONE. 6 (11): e27373. Bibcode:2011PLoSO...627373R. doi: 10.1371/journal.pone.0027373 . PMC   3210815 . PMID   22087300.
  34. ↑ Martill D.M. (1993). "Soupy Substrates: A Medium for the Exceptional Preservation of Ichthyosaurs of the Posidonia Shale (Lower Jurassic) of Germany". Kaupia - Darmstädter Beiträge zur Naturgeschichte, 2 : 77-97.
  35. ↑ Gould, Stephen Jay (1993) "Bent Out of Shape" in Eight Little Piggies: Reflections in Natural History. Norton, 179–94. ISBN   9780393311396.
  36. ↑ "Sardine Run Shark Feeding Frenzy Phenomenon in Africa". Archived from the original on 2 December 2008.
  37. ↑ "The Society for Marine Mammalogy's Taxonomy Committee List of Species and subspecies". Society for Marine Mammalogy. October 2015. Archived from the original on 6 January 2015. Retrieved 23 November 2015.
  38. ↑ Romer A. S. and Parsons T. S. (1986) The Vertebrate Body, page 96, Sanders College Publishing. ISBN   0030584469.
  39. ↑ "Blue whale". World Wide Fund For Nature. Retrieved 15 August 2016.
  40. ↑ Marino, Lori (2004). "Cetacean Brain Evolution: Multiplication Generates Complexity" (PDF). International Society for Comparative Psychology (17): 1–16. Archived from the original (PDF) on 16 September 2018. Retrieved 18 May 2019.
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