Animals

Triceratops — the three-horned Late Cretaceous ceratopsian Triceratops Large, horned herbivore of Late Cretaceous North America, noted for three facial horns, a massive skull and frill, abundant fossils across Hell Creek and other formations, and ongo…

Trichoptera (caddisflies): aquatic larvae and case-building insects Trichoptera Trichoptera, commonly called caddisflies, are an order of insects whose aquatic larvae build silk retreats or portable cases. They are ecologically important indicators of freshwat…

Trichromacy: Three-cone Color Vision in Humans and Other Animals Trichromacy Trichromacy is color vision based on three classes of cone photoreceptors. This article describes its biology, neural processing, evolutionary origins, species differences and prac…

Trilobite: an overview of the extinct marine arthropod Trilobite Trilobites were diverse, extinct marine arthropods that dominated Palaeozoic seas. Known for segmented exoskeletons and early compound eyes, they inform fossil studies of ancient m…

Tritylodonts: herbivorous cynodonts of the Mesozoic Tritylodont Tritylodonts were non‑mammalian cynodonts with distinctive three‑cusped cheek teeth; they were herbivores that persisted from the latest Triassic into the Early–Middle Cretaceous a…

Trogons and quetzals (Family Trogonidae) Trogon Trogons are colorful tropical birds of the family Trogonidae. This article summarizes their appearance, anatomy, behaviour, distribution, fossil history, nesting, taxonomy, conserv…

Troodon: small, bird-like theropod of the Late Cretaceous Troodon Troodon, a small bird-like theropod from the Late Cretaceous, is known for its large brain, sickle claw, nesting behavior and a complex taxonomic history that continues to be revis…

Troodontidae: bird‑like theropods with keen senses and complex behaviour Troodontidae Troodontidae are a group of small to medium bird‑like theropod dinosaurs known for large brains, keen senses, feathers, and well‑preserved nesting fossils from Asia and North Ameri…

Trout: biology, varieties, habitat, and human importance Trout Trout are salmonid fishes found mainly in cool freshwater habitats across the Northern Hemisphere; this article covers their taxonomy, appearance, life cycle, uses, and conservatio…

True owls (Strigidae): overview, characteristics, distribution and ecology True owl True owls (family Strigidae) are the larger of two owl families. This article explains their features, behavior, distribution, taxonomy, and differences from barn owls.

True parrots (Psittacoidea): diversity, traits and global distribution True parrots True parrots (Psittacoidea) are a major group of parrots with roughly 330 species. This article explains their features, distribution, evolution, roles in ecosystems, and how they…

Truebella: a genus of Andean true toads Truebella Truebella is a small genus of true toads in the family Bufonidae, endemic to central Peru (Ayacucho and Junín). This article summarizes its identity, habitat, taxonomy, ecology, an…

Trumpet manucode (Manucodia keraudrenii) Trumpet manucode A medium-sized bird of paradise from New Guinea and northeast Australia, notable for glossy black plumage, horn-like head tufts, a coiled trachea, and resonant trumpet-like calls.

Trumpeter swan (Cygnus buccinator) Trumpeter swan A very large North American swan noted for its deep, trumpet-like call, black bill and recovery from near-extinction through conservation and reintroduction programs.

Tsaagan — a Late Cretaceous dromaeosaurid from Mongolia Tsaagan Tsaagan is a small dromaeosaurid theropod from the Late Cretaceous of Mongolia. Known from well-preserved remains, it is closely related to Velociraptor and Linheraptor and illumin…

Tsetse fly (Glossina) — African blood‑feeding fly and disease vector Tsetse fly Tsetse flies (genus Glossina) are blood‑feeding flies in sub‑Saharan Africa that transmit trypanosome parasites, affecting humans and livestock. They have distinctive biology, ecol…

Tsintaosaurus: the crested hadrosaur from eastern Asia Tsintaosaurus Tsintaosaurus is a duck-billed (hadrosaurid) dinosaur from Late Cretaceous eastern Asia, notable for its unusual nasal crest and evidence of herbivory, locomotion, and social behav…

Tuatara — the living representatives of Rhynchocephalia Tuatara Tuatara are reptile species endemic to New Zealand, sole survivors of an ancient reptile order. This article covers their appearance, anatomy, evolution, ecology, conservation and…

Tukeit Hill frog (Allophryne ruthveni): taxonomy, range, and natural history Tukeit Hill frog Overview of the Tukeit Hill frog (Allophryne ruthveni), its placement in Allophryninae, distribution across northern South America, discovery at Tukeit Hill, and notable biological…

Tuna: biology, distribution, uses, and conservation Tuna Tuna are large, fast-swimming oceanic fish in the family Scombridae. This article covers their biology, species, behavior, human uses, and conservation concerns including fisheries…

Tunicate (Urochordata): sea squirts, life cycle, diversity and significance Tunicate Tunicates (Urochordata) are marine chordates with a protective tunic. They include sessile ascidians and planktonic salps and larvaceans, notable for filter feeding, metamorphosis…

Tupuxuara — crested pterosaur from the Santana Formation Tupuxuara Tupuxuara is a crested pterosaur from the Early Cretaceous Santana Formation of Brazil. Known for its large skull crest and variable size, its exact classification and diet remain…

Turbatrix aceti (vinegar eel): description, life cycle, habitat and uses Turbatrix aceti Turbatrix aceti, commonly called vinegar eels, are small free-living nematodes that feed on acetic bacteria in fermenting liquids. This article covers appearance, life cycle, habit…

Turbellaria — free-living flatworms Turbellaria Turbellaria are predominantly free-living flatworms found in freshwater, marine and damp terrestrial habitats. This article covers their form, behavior, reproduction, taxonomy and…

Turbot (Scophthalmus maximus): Ecology, Distribution, and Culinary Value Turbot Turbot (Scophthalmus maximus): a large demersal flatfish of the NE Atlantic, Baltic and Mediterranean coasts, prized for firm white flesh; caught wild and farmed and sold as a high…

Turdidae: the thrushes (passerine songbirds) Turdidae Turdidae, commonly called thrushes, are a group of medium-sized passerine songbirds. This article covers their traits, taxonomy, behavior, ecology, examples, and how they differ fr…

Turkey (bird): biology, species, domestication and cultural significance Turkey (bird) Large ground-dwelling birds of the genus Meleagris, native to the Americas. Overview of appearance, behavior, species, domestication, cultural roles and conservation.

Turkey vulture (Cathartes aura): widespread American scavenger Turkey vulture A common New World vulture found from Canada to the tip of South America. An obligate scavenger, the turkey vulture uses keen smell and soaring flight to locate carrion and plays a…

Turkish Angora: origin, characteristics, and distinctions Turkish Angora A graceful, ancient cat breed from Turkey known for its fine, silky coat, elegant build, lively temperament, and frequent white coloration with striking eye colors.

Turkish Van (cat breed): origin, appearance, behavior and care Turkish Van A concise encyclopedia entry on the Turkish Van: origins around Lake Van, distinctive 'Van' coat pattern, affinity for water, seasonal coat changes, temperament, care, health consi…

Turquoise-browed motmot (Eumomota superciliosa): description, range and significance Turquoise-browed motmot A compact overview of the turquoise-browed motmot (Eumomota superciliosa): identification, range, behaviour, habitat, cultural role and conservation status in Central America.

Turtle (Testudines): Anatomy, Evolution, Habitats and Conservation Turtle Turtles (order Testudines) are shelled reptiles found in marine, freshwater and terrestrial habitats. This article covers their anatomy, evolution, diversity, ecology and conservat…

Tusk: form, function, and conservation of elongated teeth Tusk A tusk is an enlarged, protruding tooth found in several mammal species. This article explains tusk structure, variations across species, uses in nature and history, and conservati…

Tweety (Tweety Bird) — Looney Tunes canary Tweety Tweety is a fictional yellow canary from Looney Tunes, known for his innocent voice, clever escapes from Sylvester, and long-running presence in animation and comics.

Twelve-wired bird‑of‑paradise (Seleucidis melanoleucus) Twelve-wired bird-of-paradise A medium-sized bird-of-paradise from New Guinea and nearby islands, notable for the male’s twelve wire-like flank filaments, striking yellow plumes, and a distinctive vertical-perc…

Tylosaurus — a large Late Cretaceous mosasaur Tylosaurus Tylosaurus was a large, predatory mosasaur from the Late Cretaceous seas of North America. This article summarizes its anatomy, fossil record, diet, notable specimens and scientifi…

Tylototriton verrucosus — Himalayan newt Tylototriton verrucosus Tylototriton verrucosus, the Himalayan newt, is a tubercled salamander of montane forests in South and Southeast Asia, notable for its dark body with orange markings, toxic skin se…

Tyranni (Suboscines): a concise overview of the suborder Tyranni Tyranni, or suboscines, are a suborder of passerine birds largely found in the Americas. They differ from songbirds in syrinx anatomy and vocal learning and include roughly 1,000 s…

Tyrannosauridae: the late Cretaceous large-bodied theropods Tyrannosauridae Tyrannosauridae is a family of large predatory theropod dinosaurs from the Late Cretaceous, known from North America and Asia; includes genera such as Tyrannosaurus, Albertosaurus…

Tyrannosaurus (tyrant lizard) Tyrannosaurus Tyrannosaurus, best known for T. rex, was a large bipedal carnivorous theropod of the Late Cretaceous, noted for its massive skull, powerful bite, debated hunting behavior, and pro…

Tyrant flycatchers (Tyrannidae): New World flycatchers and their biology Tyrant flycatcher Tyrant flycatchers (Tyrannidae) are the largest family of New World suboscine passerines, found throughout the Americas and notable for their diversity, varied feeding strategies a…

Tytonidae — the barn-owl family Tytonidae Tytonidae, commonly called barn-owls, are a distinct family of nocturnal raptors with heart-shaped faces, silent flight, and acute hearing; they occupy many habitats worldwide and…

Uakari (genus Cacajao): red-faced New World monkeys of the Amazon Uakari Uakaris are short-tailed New World monkeys in the genus Cacajao, noted for their bright red faces and specialization to Amazonian flooded forests. Several species face conservation…

Udanoceratops Udanoceratops is a Late Cretaceous neoceratopsian dinosaur known for an unusually large skull, distinctive dentition and a mix of primitive and derived traits that make its classif…

Unenlagia: a bird-like theropod from the mid-Cretaceous Unenlagia Unenlagia was a bird-like dromaeosaurid theropod from mid‑Cretaceous Patagonia (~90 Ma). Not a direct ancestor of modern birds, it shows many avian features and illustrates converg…

Ungulate: Hoofed Mammals — Definition, Biology, and Evolution Ungulate Ungulates are hoofed mammals—diverse herbivores and omnivores with specialized limbs and digestive systems. This article covers anatomy, major groups, evolution, roles in ecosystem…

Upland buzzard (Buteo hemilasius) Upland buzzard A large buzzard of open Central and East Asian highlands. Overview of identification, habitat, behaviour, diet, breeding and conservation notes for Buteo hemilasius.

Urial (Ovis orientalis vignei): wild sheep of western Central Asia Urial The urial is a wild sheep subspecies native to western Central Asia, noted for reddish coats, large male horns and conservation concerns from hunting, livestock competition and hab…