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Testudinata

Testudinata is commonly known as turtles, and all its members are the oldest reptiles in existence. They are characterized by a very strong shell on their bodies. When attacked, the turtle can retract its head, tail and limbs into the shell. Most turtles are carnivorous. Turtles can usually live on land and in water, and there are also sea turtles that live in the sea for a long time. Turtles are also long-lived animals, and some live for more than a hundred years in the natural environment.

I. Introduction to Testudines

1. Definition and Main Characteristics

  • Taxonomic Placement
    Testudines (also referred to as Chelonia in some classifications) is an order of Reptilia (reptiles) that includes all extant and extinct turtles, tortoises, and terrapins. With around 350 living species, they inhabit freshwater, marine, and terrestrial environments in tropical, temperate, and even high-elevation regions worldwide.

  • Prominent Morphological Features

    • Carapace and Plastron: The most distinctive attribute is the hard shell composed of an upper carapace (formed by expanded ribs and vertebrae) and a lower plastron, often covered by horny scutes or leathery skin.

    • Neck Retraction: Based on how the neck is retracted or bent sideways, turtles are divided into two main suborders: Cryptodira (hidden-necked turtles) and Pleurodira (side-necked turtles).

    • Toothless Jaws: Turtles lack true teeth, instead bearing sharp, horn-like beaks for feeding.

    • Longevity and Growth: Many Testudines species exhibit long lifespans and slow growth rates; some sea turtles and giant tortoises can live for decades or even over a century.

  • Ecological Habits

    • Habitat Range: Includes marine (e.g., sea turtles), freshwater (e.g., softshell turtles, pond turtles), and terrestrial (e.g., tortoises) habitats.

    • Varied Diets: Some are strictly herbivorous (many tortoises), others are omnivorous (certain freshwater turtles), and some are carnivorous (softshells, snapping turtles, leatherback turtles, etc.).

    • Reproduction: All are oviparous, laying eggs on land or sandy beaches. The hatchlings receive no parental care post-hatching.

2. Ecological and Human Significance

  • Role in Food Webs
    Freshwater and marine turtles often act as mid-level predators, scavengers, or algae grazers, helping maintain aquatic ecosystems. Tortoises can be influential herbivores in grasslands and deserts, aiding seed dispersal and soil turnover.

  • Economic and Cultural Value

    • Fisheries and Medicinal Use: Some turtles (like softshell turtles, certain freshwater species) are harvested for food or used in traditional medicine.

    • Pets and Ornamental Species: Many species (e.g., red-eared sliders, Asian box turtles, sulcata tortoises) appear in the pet trade, which can raise concerns regarding invasive species or illegal trafficking.

    • Cultural Symbol: Turtles often symbolize longevity and resilience in various cultures, while sea turtles hold important roles in marine ecotourism and folklore.


II. Evolutionary History

  1. Fossil Record and Early Origins

  • Turtles emerged as early as the Late Triassic (over 200 million years ago), as evidenced by fossils like Odontochelys, which had partly formed shells.

  • By the Jurassic, stem turtles like Proganochelys displayed a more complete shell, although retaining some primitive traits. These fossils illustrate the evolutionary path from thickened ribs and dermal plates to the robust shells we see today.

  1. Division into Hidden-necked and Side-necked Turtles

  • The difference in neck retraction strategy leads to two main lineages:

    • Cryptodira: The majority of modern turtles (sea turtles, tortoises, freshwater turtles) retract their necks straight back into the shell.

    • Pleurodira: Fewer species found mainly in the Southern Hemisphere (snake-necked and side-necked turtles) bend their necks sideways to tuck it under the shell margin.

  • This divergence dates back to the Late Jurassic or mid-Cretaceous, with each lineage evolving extensively on different continents.

  1. Modern Diversity and Distribution

  • Through subsequent geological periods, tectonic shifts and climatic changes allowed turtles to expand into marine, riverine, wetland, and desert habitats.

  • Human activities (hunting, habitat destruction, global trade) and climatic changes now pose significant threats to many turtle populations, placing numerous species under endangered or protected status.


III. Major Classification Table of Testudines

A. Suborder Pleurodira (Side-necked Turtles)

FamilyRepresentative GenusExample SpeciesDistribution & Notes
Chelidae (Austro-American Side-necked Turtles)Chelus (Mata mata), Chelodina (Long-necked turtles), etc.Mata mata (Chelus fimbriata), Australian long-necked turtle (Chelodina longicollis), etc.Found in South America and Australia; notably long necks that fold sideways, some have very unusual appearances.
Pelomedusidae (Afro-American Sideneck Turtles)Pelomedusa (African Helmeted Turtle), Pelusios, etc.African helmeted turtle (Pelomedusa subrufa), etc.Mostly in Africa, parts of South America and Madagascar; neck folds to the side rather than fully retracting.
Podocnemididae (River Turtles)Podocnemis (South American River Turtles), etc.Yellow-spotted river turtle (Podocnemis unifilis), etc.Large, riverine turtles found in South American basins and Madagascar; many species are big-bodied and aquatic.

B. Suborder Cryptodira (Hidden-necked Turtles)

FamilyRepresentative GenusExample SpeciesDistribution & Notes
Cheloniidae (Sea Turtles)Chelonia (Green Sea Turtle), Eretmochelys (Hawksbill), Caretta (Loggerhead), etc.Green sea turtle (Chelonia mydas), Hawksbill (Eretmochelys imbricata), Loggerhead (Caretta caretta), etc.Occupy tropical/subtropical oceans worldwide; threatened by fisheries bycatch, marine pollution, coastal habitat loss.
Dermochelyidae (Leatherback Sea Turtle)Dermochelys (Leatherback Turtle)Leatherback turtle (Dermochelys coriacea)The largest sea turtle; unique leathery shell instead of horny scutes; jellyfish specialist; also endangered globally.
Chelydridae (Snapping Turtles)Macrochelys (Alligator Snapping Turtle), Chelydra (Common Snapping Turtle)Alligator snapping turtle (Macrochelys temminckii), Common snapping turtle (Chelydra serpentina)Native to North America; large freshwater turtles with strong bites and aggressive temperament.
Trionychidae (Softshell Turtles)Pelodiscus (Chinese Softshell), Apalone (American Softshell), Rafetus, etc.Chinese softshell turtle (Pelodiscus sinensis), Spiny softshell (Apalone spinifera), etc.Soft, leathery carapace; well-adapted for ambush hunting and burrowing; found in Asia, Africa, North America.
Emydidae (Pond and Box Turtles)Trachemys (Sliders), Emys (European Pond Turtle), Graptemys (Map Turtles), etc.Red-eared slider (Trachemys scripta elegans), European pond turtle (Emys orbicularis), etc.Mostly in North America and parts of Europe/North Africa/Asia; popular in pet trade. Red-eared sliders can be invasive.
Testudinidae (Tortoises)Testudo (Mediterranean tortoises), Geochelone (Giant tortoises), Gopherus (Gopher tortoises), etc.Sulcata tortoise (Centrochelys sulcata), Galápagos tortoise (Chelonoidis niger), etc.Terrestrial species with strong, columnar limbs; found in arid/semi-arid regions worldwide; some are extremely long-lived.
Geoemydidae (Leaf and Pond Turtles)Mauremys (Asian Pond Turtle), Cuora (Asian Box Turtle), Sacalia, Chinemys, etc.Asian leaf turtle (Mauremys mutica), Yellow-margined box turtle (Cuora flavomarginata), etc.Mostly Asian distribution; many species threatened by habitat loss and over-collection for food or medicine.
Dermatemydidae (Mesoamerican River Turtle)Dermatemys (Giant River Turtle)Central American river turtle (Dermatemys mawii)Endemic to river systems in Central America; extremely endangered due to limited distribution and exploitation.

IV. Conclusion

  1. Multiple Evolutionary Events Shaping Global Distribution

  • The fossil record of turtles dates back to the Late Triassic, revealing the earliest shells and subsequent division into the hidden-neck (Cryptodira) and side-neck (Pleurodira) lineages.

  • These lineages diversified into marine, freshwater, and terrestrial habitats on different continents across geological time.

  1. Ecology and Human Interaction

  • Turtles play vital roles in marine and freshwater ecosystems (e.g., sea turtles controlling jellyfish populations, softshells scavenging organic matter). Tortoises are key herbivores in deserts/grasslands.

  • Overexploitation (hunting, trade), habitat loss, and pollution threaten many turtle species, making conservation efforts vital.

  1. Conservation and the Future

  • Many sea turtles and numerous freshwater/terrestrial turtles are listed under international conventions or on endangered species lists. Conservation efforts include protected areas, nesting beach patrols, captive breeding, and release programs.

  • Ongoing genetic and phylogenetic research refines our understanding of turtle relationships, guiding taxonomy, conservation priorities, and strategies.


Summary

This overview analyzes the historical evolution, main classifications, and roles of the order Testudines in ecology and human society. If you need to get more detailed information on the morphology, distribution, and conservation status of specific species, you can refer to local herpetological records, reports from wildlife conservation organizations, and the latest molecular systematics research. I hope this "Classification of Testudines" can provide you with easy-to-understand and informative popular science.

Testudines Squamata Crocodilia Lizardia
Sacalia quadriocellata

Sacalia quadriocellata

Sacalia quadriocellata,Four-eyed Turtle,Six-eyed turtle, four-eyed turtle, four-eyed spotted turtle

Features:The head and neck are brown-olive in color, with two pairs of eye spots closely arranged on the back of the head.

Four-eyed turtle is called Four-eyed Turtle in foreign language, and has no subspecies.In nature, four-eyed turtles like to live in pits and ditches in mountainous and hilly areas, and often live in dark places, such as under stones and in tree roots. The four-eyed spotted turtle is very timid. Once...

Cuora zhoui

Cuora zhoui

Cuora zhoui,Zhou`s Box Turtle,Black box turtle, black turtle

Features:Carapace is black or earthy black, with a tiny notch between the left and right hip shields

Zhou's Box Turtle is called Zhou's Box Turtle in foreign language, and has no subspecies.Zhou's Box Turtle is named after Zhou Jiufa, the director of Nanjing Wulongtan Park, who discovered this turtle species in February 1990.The living habits of wild Zhou's box turtles have not been...

Cuora yunnanensis

Cuora yunnanensis

Cuora yunnanensis,Yunnan box turtle,turtle

Features:The carapace is slightly flat, the rear edge of the plastron has a clear notch, and there are no three black vertical lines on the back

Yunnan box turtle is called Yunnan box turtle in foreign language, and has no subspecies.Yunnan box turtle was originally named after the specimen collected by foreign missionary Boulenger in Yunnan in 1906.The Yunnan box turtle lives in the plateau mountains at an altitude of 2000-2260 meters, and...

Cuora picturata

Cuora picturata

Cuora picturata,Southern Vietnam Box Turtle,Annam's box turtle

Features:Cream or yellow head, cream belly, with a large black spot on each scale

The foreign name of the patterned box turtle is Southern Vietnam Box Turtle, and there is no subspecies.The patterned box turtle was previously published as the yellow-fronted box turtle pictorial subspecies (Cuora galbinifrons picturata), and in 2004 Stuart and Parram (Stuart & Parham promoted...

Cuora pani

Cuora pani

Cuora pani,Pan's box turtle,Pan's box turtle

Features:At around 15℃, they stop eating or eat less, and below 10℃, they enter hibernation

Pan's box turtle is called Pan's box turtle in foreign language, and has no subspecies.Pan's box turtle is the northernmost species of the genus Pan's box turtle in China. It was first discovered in 1981 in a ditch beside a rice field at an altitude of 420 meters in Xujiaba, Pingli C...

Cuora mouhotii

Cuora mouhotii

Cuora mouhotii,Keeled Box Turtle,Saw-edged box turtle, octagonal turtle, octagonal turtle, square turtle, saw-edged box turtle

Features:It likes warmth and is afraid of cold. The front and rear edges of the carapace have serrated shields.

Keeled Box Turtle has two subspecies.Keeled Box Turtle feeds on animals, but also plants, especially live food, such as locusts, mealworms, earthworms, etc. It likes warmth and is afraid of cold. It hibernates when the ambient temperature is 19℃, eats normally at 25℃, and eats the most at 28-31℃....

Cuora mccordi

Cuora mccordi

Cuora mccordi,Bose box terrapin,Mccord's Box Turtle,MacArthur's box turtle

Features:It is named after its origin near Baise City in Guangxi.

Bose box turtle is called Bose box terrapin in English, and has no subspecies.The Baise Box Turtle was named by C.H Emst in August 1988 based on the specimens purchased from the west of Baise City, Guangxi, China, near the border of Yunnan. Because its origin is near Baise City, Guangxi, the Chinese...

Cuora galbinifrons

Cuora galbinifrons

Cuora galbinifrons,Indochinese Box Turtle,Hainan box turtle, yellow-fronted box turtle

Features:The dry season has a hibernation period of nearly 4 months

The foreign name of the yellow-fronted box turtle is Indochinese Box Turtle, and there is no subspecies.The yellow-fronted box turtle likes to live in streams and shallow water areas in hilly and mountainous areas, and often hides in fallen leaves under the forest. It is diurnal and often lives by s...

Cuora flavomarginata

Cuora flavomarginata

Cuora flavomarginata,Yellow-margined Box Turtle, splint turtle, snake-killing turtle, broken plate turtle, yellow-margined box turtle

Features:Likes to live in groups and is not afraid of people

Yellow-margined Box Turtle has two subspecies.Yellow-margined Box Turtle is bolder than other freshwater turtles and is not afraid of people. Except for the mating season, it rarely fights with its own kind. After one month of domestication, individuals can develop the habit of eating at regular tim...

Cuora trifasciata

Cuora trifasciata

Cuora trifasciata,Chinese Three-striped Box Turtle,Golden coin turtle, golden head turtle, red edge turtle, red belly turtle, broken board turtle, Sichuan back turtle

Features:It is an edible turtle species in southern China and is also commonly used as medicine by the people.

The three-striped box turtle is called Chinese Three-striped Box Turtle in English, and there are 2 subspecies.The two subspecies of the three-striped box turtle have similar diets and other biological characteristics. The Vietnamese subspecies is more adaptable and grows faster than the Hainan subs...

Cuora bourreti

Cuora bourreti

Cuora bourreti,Bourett's Box Turtle,Brandt's box turtle,Bourett's Box Turtle,Cuora galbinifrons bourreti Obst & Reimann

Features:The head color is brighter, the body is larger than the patterned closed-shell turtle, and is elongated and oval.

Bourett's Box Turtle is a medium-sized land turtle.The Bourreti box turtle was previously published as Cuora galbinifrons bourreti, and was first described by Stuart and Parram in 2004. Parham promoted it to an independent species; in 2006, Fritz et al. questioned its independent species status;...

Golden-headed Box Turtle

Golden-headed Box Turtle

Golden-headed Box Turtle,Golden turtle, splint turtle, yellow turtle

Features:The head is golden yellow, with slightly yellowish brown on the sides and three thin black stripes

Golden-headed Box Turtle, with two subspecies.In the late 1980s, Luo Bitao and Zong Yu, based on the No. 3 model specimen obtained from Nanling, believed that the turtle belonged to a new species of box turtles and named it the golden-headed box turtle based on the morphological taxonomy of turtles....

Cuora amboinensis

Cuora amboinensis

Southeast Asian Box Turtle,Southeast Asian Box Turtle,Humpback turtle, Vietnamese turtle, Ambu box turtle

Features:They like to live in water and do not fight for food or bite each other.

The Southeast Asian Box Turtle has four subspecies.In his book The Reptiles of China, Pope (1935) mentioned two specimens of the Malayan Box Turtle from China, which were preserved in a Paris museum, but their origin was unknown. Cen Jianqiang and Tang Jun (1992) reported that they bought four Malay...

Scatophagus argus

Scatophagus argus

Scatophagus argusThree-lined box turtle, red-sided turtle, red-bellied turtle, broken plate turtle, golden-headed turtle

Features:It has a golden appearance, a red base, and a docile personality, making it suitable as a pet.

The scientific name of the golden coin turtle is the three-lined box turtle (Cuora trifasciata), which belongs to the order Testudinata, family Testudinidae, subfamily Testudininae, genus Testudinata, and is a second-class protected animal in my country. The golden coin turtle is a precious animal r...

Rafetus swinhoei

Rafetus swinhoei

Rafetus swinhoei,Yangtze Giant Softshell Turtle;Swinhoe's softshell,Rùa Hồ Gươm,Taihu turtle, giant softshell turtle, spotted softshell turtle, and Stuart softshell turtle

Features:The head, neck and back of the limbs are also dark green with irregular yellow spots of different sizes. This dense yellow pattern is a characteristic of the Yangtze giant softshell turtle.

In ancient times, the Yangtze giant softshell turtle was widely distributed in the lower reaches of the Yangtze River and the Taihu Lake area in China. The ancients called it the 癞头缋. Due to wanton hunting and ecological damage, no wild individuals have been found since 1972. There are only two c...

Palea steindachneri

Palea steindachneri

Palea steindachneri,wattle-necked softshell turtle,Trionyx steindachneri Siebenrock,Mountain Rui, Rui fish, soft-shelled turtle, round fish, turtle, tortoise

Features:Its appearance is very similar to that of the Chinese soft-shelled turtle, commonly known as "turtle". It is round in shape, but slightly larger and thicker.

The mountain softshell turtle is a cold-blooded animal. When the temperature drops to 12℃, it will hibernate under the sand or stones, so people also call it the sand softshell turtle. When the temperature rises to 18-20℃ in the next spring, it will wake up and start looking for food. The optimum...

Pelochelys cantorii

Pelochelys cantorii

Pelochelys cantorii,Frog-faced Softshell Turtle、Asian Giant Soft-shelled Turtle、Cantor's Giant Softshell,Blue grouper, silver fish, green grouper, giant turtle, spotted turtle, Cantor's gian

Features:The largest species of turtle, it has a relatively small head and small eyes. It likes to live in groups and has a long lifespan.

Before and after the release of the "List of National Key Protected Wildlife in China" in 1989, according to the "Fauna Sinica", all giant freshwater turtles in China were called "turtles". Therefore, the turtle (then scientific name Pelochelys bibroni), which was liste...

Dermochelys coriacea

Dermochelys coriacea

Dermochelys coriacea,Leatherback Turtle,Leatherback turtle, seven-winged turtle, sampan turtle, swallow turtle, leatherback turtle

Features:The largest of the order Testudinata, its body and limbs are covered with irregular polygonal scales. The largest is found in

The leatherback turtle is large and is the largest turtle in the world. It has a large head, short neck and tail, paddle-shaped limbs, no claws, and particularly developed forelimbs.The leatherback turtle is a cold-blooded reptile that swims fast and has strong ability. It is omnivorous and lays egg...

Lepidochelys olivacea

Lepidochelys olivacea

Lepidochelys olivacea,Olive Ridley, Pacific Ridley,Ridley du Pacifique, Tortue Bâtarde, Tortue Olivâtre, Tartaruga-comum, Tartaruga-oliva, Tartaruga-pequena,Tortue de Ridley,Tortuga Carpintera, Tortug

Features:The limbs are flat like paddles. The head, limbs and back of the body are dark olive green, and the plastron is light orange-yellow.

The Olive Ridley is marine and little is known about its behavior other than its regular annual trips to nesting beaches. It feeds in the morning and basks on the surface in the afternoon. Large groups of turtles gather together to bask in the afternoon to escape the freezing temperatures of the wat...

Eretmochelys imbricata

Eretmochelys imbricata

Eretmochelys imbricata, Hawksbill Turtle,Caret, Tortue Caret, Tortue imbriquée, Tortue à bec faucon, Tortue à écailles,Tortuga de Carey,سلحفاة صقرية المنقار

Features:It likes heat and fears cold, and can live up to 1,500 years, making it one of the longest-lived animals.

Hawksbill turtles are an animal that often migrates. They are highly mobile and swim fast. They are large and fierce carnivorous animals in the ocean and often appear in coral reefs. Hawksbill turtles have strong adaptability and resistance to their prey. Some of the sponges they feed on are highly...

Chelonia mydas

Chelonia mydas

Chelonia mydas,Green Turtle,Sea turtle, black turtle, stone turtle

Features:One of the largest hard-shelled sea turtles, it is named for the green color of its fat.

The green turtle, also known as the sea turtle, is one of the larger species of sea turtles. It is named because its body fat is rich in chlorophyll, the main food of seaweed. The gender of adult turtles is easy to identify, and the length of the tail is a gender characteristic. Generally speaking,...