Substance abuse prevention

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https://en.wikipedia.org/wiki/Substance_abuse_prevention

Rational scale to assess the harm of drugs

Substance abuse prevention, also known as drug abuse prevention, is a process that attempts to prevent the onset of substance use or limit the development of problems associated with using psychoactive substances. Prevention efforts may focus on the individual or their surroundings. A concept that is known as "environmental prevention" focuses on changing community conditions or policies so that the availability of substances is reduced as well as the demand. Individual Substance Abuse Prevention, also known as drug abuse prevention involves numerous different sessions depending on the individual to help cease or reduce the use of substances. The time period to help a specific individual can vary based upon many aspects of an individual. The type of Prevention efforts should be based upon the individual's necessities which can also vary. Substance use prevention efforts typically focus on minors and young adults – especially between 12–35 years of age. Substances typically targeted by preventive efforts include alcohol (including binge drinking, drunkenness and driving under the influence), tobacco (including cigarettes and various forms of smokeless tobacco), marijuana, inhalants (volatile solvents including among other things glue, gasoline, aerosols, ether, fumes from correction fluid and marking pens), coke, methamphetamine, steroids, club drugs (such as MDMA), and opioids. Community advocacy against substance use is imperative due to the significant increase in opioid overdoses in the United States alone. It has been estimated that about one hundred and thirty individuals continue to lose their lives daily due to opioid overdoses alone.

Protective and risk factors

Environmental and internal are two main factors that contribute to the likelihood of developing a substance use disorder. Environmental factors in the individual's adolescence include: child abuse, exposure to substances, lack of supervision, media influence, and peer pressure. Drug activity in an individual's community may normalize the usage of drugs. The result of substance use can be caused do to stressful situations within household which can result of learned behavior of the is of substances to cope. Similarly. if an individual is placed through treatment and then placed back into the same environment that they left, there is a great chance that person will relapse to their previous behavior. Internal factors that are within the child or personality-based are self-esteem, poor social skills, stress, attitudes about drugs, mental disorder and many others. A few more factors that contribute to teen drug abuse are lack of or poor parent to child communication, unsupervised accessibility of alcohol at home, having too much freedom and being left alone for long periods of time. Additionally, there is evidence that gender moderates the effect of family, school and peer factors on adolescent substance use. For example, some studies report that not living with both biological parents or having poor parent-adolescent communication is associated with substance use, especially in female adolescents.

Main risk periods for substance use occur during major transitions in a child's life. Some of these transitional periods that could increase the possibility of youth using drugs are puberty, moving, divorce, leaving the security of the home, and entering school. School transitions such as those from elementary to middle school or middle school to high school can be times that children and teenagers make new friends and are more susceptible to fall into environments where there are drugs available. One recent study examined that by the time are seniors in high school, "almost 70 percent will have tried alcohol, half will have taken an illegal drug, nearly 40 percent will have smoked a cigarette, and more than 20 percent will have used a prescription drug for a nonmedical purpose” (Johnston et al., 2013). Binge drinking has also, been shown to increase once an individual leaves the home to attend college or live on their own.

Most youths do not progress towards regular, heavy substance use after experimentation. Research has shown, when drug use begins at an early age, there is a greater possibility for addiction to occur. Three exacerbating factors that can influence substance use to become substance use are social approval, lack of perceived risks, and availability of drugs in the community. Youths from certain demographics are also at higher risk for addiction. These groups include those suffering from a mental illness and who comes from a family history of addiction. Yet, some teens living with dual diagnosis prove that there is not always a causal relationship between mental illness and a substance use disorder. Moreover, when addiction occurs, youth are more likely to require teen rehab as a form of treatment. Most young adults have a false perception that they may be invincible. These individuals believe changes won't be made until an extreme event happens i.e. a friend overdoses, a car accident or even death. Even then it is not likely that they will see the correlation between use and trauma.

Substance use includes risk factors that correlate to one's health that can include HIV/AIDS, Hepatitis B virus, and Hepatitis C virus. These viral infections can be easily be spread by injections from needles.

Plans on preventing substance use

Family based prevention programs

"Prevention programs can strengthen protective factors among young children by teaching parents better family communication skills, appropriate discipline styles, firm, and consistent rule enforcement, and other family management approaches. Research confirms the benefits of parents providing consistent rules and discipline, talking to children about drugs, monitoring their activities, getting to know their friends, understanding their problems and concerns, and being involved in their learning. The importance of the parent-child relationship continues through adolescence and beyond" (National Institute of Drug Abuse, 2003). Research has been done showing that the measures taken within family prevention has been shown to reduce the risk of substance abuse.

Smit, Verdurmen, Monshouwer, and Smil conducted research analysis to measure the effectiveness of family interventions about teen and adolescence drug and alcohol use. According to their data, use of alcohol and other drugs is very common in Western societies. For example, 18% of the young adults between the ages of 12–14 years old in the US have indulged in binge drinking. According to quantities in 2006, 73% of 16-year-old US students were reported having used alcohol; In Northern Europe, this is 90%. Since early use of alcohol and other substances may cause serious health, immediate solutions to these problem are required .

School-based prevention programs

US Navy Master-at-Arms 1st Class Michael Turner of Mobile Security Squadron Two (MSS-2) collects information at the Substance Abuse Prevention Summit

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Drama based education to motivate participation in substance use prevention. (media from BioMed Central)

There are a number of community-based prevention programs and classes that aim to educate children and families about the harms of substance use. Schools began introducing substance use oriented classes for their students in grades as low as preschool. The inclusion of prevention studies into classroom curricula at a young age has been shown to help to break early behaviors that could be signs of an increased risk for developing a substance use disorder in the future. Around 40% of children have tried alcohol by the time that they are ten.

Many organizations educate, advocate, and collaborate to prevent substance use. Some programs may begin by allowing students to be interactive and learn skills such as how to refuse drugs. This is proven to be a more effective method than strictly educational or non-interactive ones. When direct influences (e.g., peers) and indirect influences (e.g., media influence) are addressed, the program is better able to cover broad social influences that most programs do not consider. Programs that encourage a social commitment to abstain from drugs show lower rates of drug use. Getting the community outside of the school to participate and also using peer leaders to facilitate the interactions tend to be an effective facet of these programs. Even though adolescents are frequently aware of the negative consequences of substance use, they may start and maintain this habit. Adolescents, their parents, and other family members are the focus of comprehensive preventive and control programs in schools and the community. These effective actions help promote children's development of a positive sense of self-worth and sufficiency, to stop adolescent risk behavior, and to help them build strong, healthy coping skills. Lastly, teaching youth and adolescents skills that increase resistance skills in social situations may increase protective factors in that population.

Community prevention programs

Prevention programs work at the community level with civic, religious, law enforcement, and other government organizations to enhance anti-drug norms and pro-social behaviors. Many programs help with prevention efforts across settings to help send messages through school, work, religious institutions, and the media. Research has shown that programs that reach youth through multiple settings can remarkably influence community norms. Community-based programs also typically include the development of policies or enforcement of regulations, mass media efforts, and community-wide awareness programs. Increasing health education in the community also plays a role in helping to decrease the consequences of substance use.

On a community level, established safe injection sites that provide a hygienic space supervised by licensed healthcare professionals allow for safe monitoring of participants and provide health education and care to prevent overdose. Another way to help prevent overdose, especially regarding opioids, is the increased access and knowledge of naloxone. Naloxone is the standard opioid overdose reversal agent. Studies show Overdose Education and Naloxone Distribution (OEND) programs decrease the rate of rate of deaths from opioid overdose. Naloxone comes in different routes of administration such as, an injection that's administered intravenously, intramuscular, or subcutaneously and a nasal spray. Naloxone injection and the nasal spray are both commonly used in adults and children who are going through drug overdose because it is successful in reversing the overdose effects.  As a safety precaution, patients taking opioids are recommended to always carry naloxone with them and should replace the naloxone regularly, via reference to the expiration date. Research has shown that extra effort in providing incentives, flexible schedules, personal contact, and the public support of important community leaders helps attract and retain program participants.

Medical-based prevention programs

Prevention within the medical field plays a large role in impeding substance abuse. This is largely seen when looking at the role nurses play in the opioid crisis in the United States. One program that nurses can get involved with regarding the opioid epidemic is medication-assisted treatment (MAT) system. This system is an evidence based approach that uses both therapy and medication to treat patients struggling with opioid addiction. Special training is required for nurses who want to participate in this program, meaning there are a limited number of nurses who can partake, however, it has greatly reversed the number of overdoses and deaths from opioids in the United States. Another type of program that nurses can assist in to reduce opioid addiction is called "eat, sleep, console." This is an approach that nurses can take when treating patients that can reduce which medications a patient needs and how long their hospital stay is. This is used for newborns that became exposed to opioids in utero, and it gives nurses the opportunity to educate their patients on how to reduce the side effects of addiction. Looking at it in whole, there are several different programs within the medical field that are used to treat substance abuse.

Levels of Prevention

There are three types of prevention which are all aimed to help reduce and or help deal with health problems that can be caused by substance use. The first intervention when dealing with substance use is primary use which involves ceasing the result of substances being used before it happens. Examples of primordial prevention include preventing the development of risk factors (e.g., depression) that increase a person's chances of developing a future substance use disorder. Examples of primary substance prevention would be the promotion of no interaction with the drug. Tertiary prevention is when the individual has to receive treatment for the substance that has been consumed. Examples include rehab & intensive outpatient therapy are examples of a few short-term preventions. Tertiary prevention involves an individual such as one suffering from substance use to receive treatment such as rehab or an intensive therapy but the process of recuperating will be longer due to the intense amount of intake within the body.

National recognition of substance use prevention

In 2011 President Obama issued October as National Substance Abuse Prevention Month. It pays tribute to all people working hard to prevent use in communities and working hard to make a safer drug-free country. 

Millions of Americans currently participate in Red Ribbon Week activities, according to the National Family Partnership (NFP)—the Red Ribbon campaign's national organizer. The Drug Enforcement Administration, a Federal partner in Red Ribbon Week, describes it as “the most far-reaching and well-known drug prevention event in America.” Through the efforts of the NFP, other national organizations, Federal and State agencies, and communities, Red Ribbon Week has become more than a call to action. It has grown to be a unifying symbol of family and community dedication to preventing the use of alcohol, tobacco, and illicit drugs among youth.

In 2017, the FDA created the Opioid Policy Steering Committee (OPSC) to help guide FDA efforts in fighting this opioid epidemic specifically focusing on topics of new addiction, treatment support and development, assessment of risk over benefit and overall enforcement.

In the United States, there is a Substance Abuse and Mental Health Services Administration that provides a free 365 days per year 24-hour phone service. Their purpose is to provide information or therapy referrals to anyone experiencing substance use disorders or mental health issues. This national helpline number is (1800-662-HELP (4357)).

The NIH has made research-based guides available to help prevent substance use and addiction in youth. One guide speaks on prevention for early childhood. Another talks about prevention in children and adolescents.

Successful intervention programs typically involve high levels of interactivity, time-intensity, and universal approaches that are delivered in the middle school years. These program characteristics aligned with many of the effective program elements found in previous reviews exploring the impact of school-based drug prevention on licit drug use.

More recently, a $3.3 billion federal spending bill has been passed by Congress, which will be used to support prevention, treatment, and law enforcement activities, supporting state and local governments.

Triassic

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Triassic

Triassic
251.902 ± 0.024 – 201.4 ± 0.2 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Chronology
−255 — – −250 — – −245 — – −240 — – −235 — – −230 — – −225 — – −220 — – −215 — – −210 — – −205 — – −200 — Pz Mesozoic Permian Triassic Jurassic Ear Middle Late Olenekian Induan Anisian Ladinian Carnian Norian Rhaetian         ← Permian-Triassic extinction event ← Smithian–Spathian boundary event ← Carnian pluvial episode ← Full recovery of woody trees ← Coals return ← Scleractinian corals & calcified sponges ← Triassic–Jurassic extinction event ← Manicouagan impact Subdivision of the Triassic according to the ICS, as of 2021. Vertical axis scale: millions of years ago.
Etymology
Name formality	Formal
Usage information
Celestial body	Earth
Regional usage	Global (ICS)
Time scale(s) used	ICS Time Scale
Definition
Chronological unit	Period
Stratigraphic unit	System
Time span formality	Formal
Lower boundary definition	First appearance of the conodont Hindeodus parvus
Lower boundary GSSP	Meishan, Zhejiang, China 31.0798°N 119.7058°E
Lower GSSP ratified	2001[6]
Upper boundary definition	First appearance of the ammonite Psiloceras spelae tirolicum
Upper boundary GSSP	Kuhjoch section, Karwendel mountains, Northern Calcareous Alps, Austria 47.4839°N 11.5306°E
Upper GSSP ratified	2010[7]

The Triassic (/traɪˈæsɪk/ try-ASS-ik; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago (Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is the first and shortest period of the Mesozoic Era. Both the start and end of the period are marked by major extinction events. The Triassic Period is subdivided into three epochs: Early Triassic, Middle Triassic and Late Triassic.

The Triassic began in the wake of the Permian–Triassic extinction event, which left the Earth's biosphere impoverished; it was well into the middle of the Triassic before life recovered its former diversity. Three categories of organisms can be distinguished in the Triassic record: survivors from the extinction event, new groups that flourished briefly, and other new groups that went on to dominate the Mesozoic Era. Reptiles, especially archosaurs, were the chief terrestrial vertebrates during this time. A specialized subgroup of archosaurs, called dinosaurs, first appeared in the Late Triassic but did not become dominant until the succeeding Jurassic Period. Archosaurs that became dominant in this period were primarily pseudosuchians, ancestors of modern crocodilians, while some archosaurs specialized in flight, the first time among vertebrates, becoming the pterosaurs.

Therapsids, the dominant vertebrates of the preceding Permian period, declined throughout the period. The first true mammals, themselves a specialized subgroup of therapsids, also evolved during this period. The vast supercontinent of Pangaea existed until the mid-Triassic, after which it began to gradually rift into two separate landmasses, Laurasia to the north and Gondwana to the south.

The global climate during the Triassic was mostly hot and dry, with deserts spanning much of Pangaea's interior. However, the climate shifted and became more humid as Pangaea began to drift apart. The end of the period was marked by yet another major mass extinction, the Triassic–Jurassic extinction event, that wiped out many groups, including most pseudosuchians, and allowed dinosaurs to assume dominance in the Jurassic.

Etymology

The Triassic was named in 1834 by Friedrich August von Alberti, after a succession of three distinct rock layers (Greek triás meaning 'triad') that are widespread in southern Germany: the lower Buntsandstein (colourful sandstone), the middle Muschelkalk (shell-bearing limestone) and the upper Keuper (coloured clay).

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  Early Triassic sandstone (Buntsandstein) near Stadtroda, Germany

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  Middle Triassic Muschelkalk (shell-bearing limestone) near Dörzbach, Germany

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  Late Triassic Steigerwald Formation and overlying Hassberge Formation in Schönbuch, Germany

Dating and subdivisions

On the geologic time scale, the Triassic is usually divided into Early, Middle, and Late Triassic Epochs, and the corresponding rocks are referred to as Lower, Middle, or Upper Triassic. The faunal stages from the youngest to oldest are:

Series/Epoch	Faunal stage	Time span
Upper/Late Triassic (Tr3)	Rhaetian	(208.5 – 201.4 ± 0.2 Mya)
	Norian	(227 – 208.5 Mya)
	Carnian	(237 – 227 Mya)
Middle Triassic (Tr2)	Ladinian	(242 – 237 Mya)
	Anisian	(247.2 – 242 Mya)
Lower/Early Triassic (Scythian)	Olenekian	(251.2 – 247.2 Mya)
	Induan	(251.902 ± 0.024 – 251.2 Mya)

Paleogeography

View of the Tethys area during the Ladinian stage (230 Ma)

230 Ma continental reconstruction

During the Triassic, almost all the Earth's land mass was concentrated into a single supercontinent, Pangaea (lit. 'entire land'). This supercontinent was more-or-less centered on the equator and extended between the poles, though it did drift northwards as the period progressed. Southern Pangea, also known as Gondwana, was made up by closely-appressed cratons corresponding to modern South America, Africa, Madagascar, India, Antarctica, and Australia. North Pangea, also known as Laurussia or Laurasia, corresponds to modern-day North America and the fragmented predecessors of Eurasia.

The western edge of Pangea lay at the margin of an enormous ocean, Panthalassa (lit. 'entire sea'), which roughly corresponds to the modern Pacific Ocean. Practically all deep-ocean crust present during the Triassic has been recycled through the subduction of oceanic plates, so very little is known about the open ocean from this time period. Most information on Panthalassan geology and marine life is derived from island arcs and rare seafloor sediments accreted onto surrounding land masses, such as present-day Japan and western North America.

The eastern edge of Pangea was encroached upon by a pair of extensive oceanic basins: The Neo-Tethys (or simply Tethys) and Paleo-Tethys Oceans. These extended from China to Iberia, hosting abundant marine life along their shallow tropical peripheries. They were divided from each other by a long string of microcontinents known as the Cimmerian terranes. Cimmerian crust had detached from Gondwana in the early Permian and drifted northwards during the Triassic, enlarging the Neo-Tethys Ocean which formed in their wake. At the same time, they forced the Paleo-Tethys Ocean to shrink as it was being subducted under Asia. By the end of the Triassic, the Paleo-Tethys Ocean occupied a small area and the Cimmerian terranes began to collide with southern Asia. This collision, known as the Cimmerian Orogeny, continued into the Jurassic and Cretaceous to produce a chain of mountain ranges stretching from Turkey to Malaysia.

Sydney, Australia lies on Triassic shales and sandstones. Almost all of the exposed rocks around Sydney belong to the Triassic Sydney sandstone.

Pangaea was fractured by widespread faulting and rift basins during the Triassic—especially late in that period—but had not yet separated. The first nonmarine sediments in the rift that marks the initial break-up of Pangaea, which separated eastern North America from Morocco, are of Late Triassic age; in the United States, these thick sediments comprise the Newark Supergroup. Rift basins are also common in South America, Europe, and Africa. Terrestrial environments are particularly well-represented in the South Africa, Russia, central Europe, and the southwest United States. Terrestrial Triassic biostratigraphy is mostly based on terrestrial and freshwater tetrapods, as well as conchostracans ("clam shrimps"), a type of fast-breeding crustacean which lived in lakes and hypersaline environments.

Because a supercontinent has less shoreline compared to a series of smaller continents, Triassic marine deposits are relatively uncommon on a global scale. A major exception is in Western Europe, where the Triassic was first studied. The northeastern margin of Gondwana was a stable passive margin along the Neo-Tethys Ocean, and marine sediments have been preserved in parts of northern India and Arabia. In North America, marine deposits are limited to a few exposures in the west.

Scandinavia

During the Triassic peneplains are thought to have formed in what is now Norway and southern Sweden. Remnants of this peneplain can be traced as a tilted summit accordance in the Swedish West Coast. In northern Norway Triassic peneplains may have been buried in sediments to be then re-exposed as coastal plains called strandflats. Dating of illite clay from a strandflat of Bømlo, southern Norway, have shown that landscape there became weathered in Late Triassic times (c. 210 million years ago) with the landscape likely also being shaped during that time.

Paleooceanography

Eustatic sea level in the Triassic was consistently low compared to the other geological periods. The beginning of the Triassic was around present sea level, rising to about 10–20 metres (33–66 ft) above present-day sea level during the Early and Middle Triassic. Sea level rise accelerated in the Ladinian, culminating with a sea level up to 50 metres (164 ft) above present-day levels during the Carnian. Sea level began to decline in the Norian, reaching a low of 50 metres (164 ft) below present sea level during the mid-Rhaetian. Low global sea levels persisted into the earliest Jurassic. The long-term sea level trend is superimposed by 22 sea level drop events widespread in the geologic record, mostly of minor (less than 25-metre (82 ft)) and medium (25–75-metre (82–246 ft)) magnitudes. A lack of evidence for Triassic continental ice sheets suggest that glacial eustasy is unlikely to be the cause of these changes.

Climate

The Triassic continental interior climate was generally hot and dry, so that typical deposits are red bed sandstones and evaporites. There is no evidence of glaciation at or near either pole; in fact, the polar regions were apparently moist and temperate, providing a climate suitable for forests and vertebrates, including reptiles. Pangaea's large size limited the moderating effect of the global ocean; its continental climate was highly seasonal, with very hot summers and cold winters. The strong contrast between the Pangea supercontinent and the global ocean triggered intense cross-equatorial monsoons, sometimes referred to as megamonsoons.

The Triassic may have mostly been a dry period, but evidence exists that it was punctuated by several episodes of increased rainfall in tropical and subtropical latitudes of the Tethys Sea and its surrounding land. Sediments and fossils suggestive of a more humid climate are known from the Anisian to Ladinian of the Tethysian domain, and from the Carnian and Rhaetian of a larger area that includes also the Boreal domain (e.g., Svalbard Islands), the North American continent, the South China block and Argentina.

The best-studied of such episodes of humid climate, and probably the most intense and widespread, was the Carnian Pluvial Event. A 2020 study found bubbles of carbon dioxide in basaltic rocks dating back to the end of the Triassic, and concluded that volcanic activity helped trigger climate change in that period.

Flora

Triassic flora as depicted in Meyers Konversations-Lexikon (1885–90)

Land plants

On land, the surviving vascular plants included the lycophytes, the dominant cycadophytes, ginkgophyta (represented in modern times by Ginkgo biloba), ferns, horsetails and glossopterids. The spermatophytes, or seed plants, came to dominate the terrestrial flora: in the northern hemisphere, conifers, ferns and bennettitales flourished. The seed fern genus Dicroidium would dominate Gondwana throughout the period.

Coal

Immediately above the Permian–Triassic boundary the glossopteris flora was suddenly largely displaced by an Australia-wide coniferous flora.

No known coal deposits date from the start of the Triassic Period. This is known as the Early Triassic "coal gap" and can be seen as part of the Permian–Triassic extinction event. Possible explanations for the coal gap include sharp drops in sea level at the time of the Permo-Triassic boundary; acid rain from the Siberian Traps eruptions or from an impact event that overwhelmed acidic swamps; climate shift to a greenhouse climate that was too hot and dry for peat accumulation; evolution of fungi or herbivores that were more destructive of wetlands; the extinction of all plants adapted to peat swamps, with a hiatus of several million years before new plant species evolved that were adapted to peat swamps; or soil anoxia as oxygen levels plummeted.

Phytoplankton

Before the Permian extinction, Archaeplastida (red and green algae) had been the major marine phytoplanktons since about 659–645 million years ago, when they replaced marine planktonic cyanobacteria, which first appeared about 800 million years ago, as the dominant phytoplankton in the oceans. In the Triassic, secondary endosymbiotic algae became the most important plankton.

Fauna

Middle Triassic marginal marine sequence, southwestern Utah

Reconstruction of the Triassic amphibian Mastodonsaurus

Marine invertebrates

In marine environments, new modern types of corals appeared in the Early Triassic, forming small patches of reefs of modest extent compared to the great reef systems of Devonian or modern times. Serpulids appeared in the Middle Triassic. Microconchids were abundant. The shelled cephalopods called ammonites recovered, diversifying from a single line that survived the Permian extinction. Bivalves began to rapidly diversify during the Middle Triassic, becoming highly abundant in the oceans.

Fish

The fish fauna was remarkably uniform, with many families and genera exhibiting a global distribution in the wake of the Permian-Triassic mass extinction event. Ray-finned fishes (actinopterygians) went through a remarkable diversification during the Triassic, leading to peak diversity during the Middle Triassic; however, the pattern of this diversification is still not well understood due to a taphonomic megabias. Large predatory actinopterygians such as saurichthyids and birgeriids appeared in the Early Triassic and became widespread and successful during the period as a whole. Lakes and rivers were populated by lungfish (Dipnoi), such as Ceratodus, which are mainly known from the dental plates, abundant in the fossils record. Hybodonts, a group of shark-like cartilaginous fish, were dominant in both freshwater and marine environments throughout the Triassic.

Amphibians

Temnospondyl amphibians were among those groups that survived the Permian–Triassic extinction. Once abundant in both terrestrial and aquatic environments, the terrestrial species had mostly died out during the extinction event. The Triassic survivors were aquatic or semi-aquatic, and were represented by Tupilakosaurus, Thabanchuia, Branchiosauridae and Micropholis, all of which died out in Early Triassic, and the successful Stereospondyli, with survivors into the Cretaceous Period. The largest Triassic stereospondyls, such as Mastodonsaurus, were up to 4 to 6 metres (13 to 20 ft) in length. Some lineages (e.g. trematosaurs) flourished briefly in the Early Triassic, while others (e.g. capitosaurs) remained successful throughout the whole period, or only came to prominence in the Late Triassic (e.g. Plagiosaurus, metoposaurs).

The first Lissamphibians (modern amphibians) appear in the Triassic, with the progenitors of the first frogs already present by the Early Triassic. However, the group as a whole did not become common until the Jurassic, when the temnospondyls had become very rare.

Most of the Reptiliomorpha, stem-amniotes that gave rise to the amniotes, disappeared in the Triassic, but two water-dwelling groups survived: Embolomeri that only survived into the early part of the period, and the Chroniosuchia, which survived until the end of the Triassic.

Reptiles

Archosauromorphs

The Permian–Triassic extinction devastated terrestrial life. Biodiversity rebounded as the surviving species repopulated empty terrain, but these were short-lived. Diverse communities with complex food-web structures took 30 million years to reestablish. Archosauromorph reptiles, which had already appeared and diversified to an extent in the Permian Period, exploded in diversity as an adaptive radiation in response to the Permian-Triassic mass extinction. By the Early Triassic, several major archosauromorph groups had appeared. Long-necked, lizard-like early archosauromorphs were known as protorosaurs, which is likely a paraphyletic group rather than a true clade. Tanystropheids were a family of protorosaurs which elevated their neck size to extremes, with the largest genus Tanystropheus having a neck longer than its body. The protorosaur family Sharovipterygidae used their elongated hindlimbs for gliding. Other archosauromorphs, such as rhynchosaurs and allokotosaurs, were mostly stocky-bodied herbivores with specialized jaw structures.

Rhynchosaurs, barrel-gutted herbivores, thrived for only a short period of time, becoming extinct about 220 million years ago. They were exceptionally abundant in the middle of the Triassic, as the primary large herbivores in many Carnian-age ecosystems. They sheared plants with premaxillary beaks and plates along the upper jaw with multiple rows of teeth. Allokotosaurs were iguana-like reptiles, including Trilophosaurus (a common Late Triassic reptile with three-crowned teeth), Teraterpeton (which had a long beak-like snout), and Shringasaurus (a horned herbivore which reached a body length of 3–4 metres (9.8–13.1 ft).

One group of archosauromorphs, the archosauriforms, were distinguished by their active predatory lifestyle, with serrated teeth and upright limb postures. Archosauriforms were diverse in the Triassic, including various terrestrial and semiaquatic predators of all shapes and sizes. The large-headed and robust erythrosuchids were among the dominant carnivores in the early Triassic. Phytosaurs were a particularly common group which prospered during the Late Triassic. These long-snouted and semiaquatic predators resemble living crocodiles and probably had a similar lifestyle, hunting for fish and small reptiles around the water's edge. However, this resemblance is only superficial and is a prime-case of convergent evolution.

True archosaurs appeared in the early Triassic, splitting into two branches: Avemetatarsalia (the ancestors to birds) and Pseudosuchia (the ancestors to crocodilians). Avemetatarsalians were a minor component of their ecosystems, but eventually produced the earliest pterosaurs and dinosaurs in the Late Triassic. Early long-tailed pterosaurs appeared in the Norian and quickly spread worldwide. Triassic dinosaurs evolved in the Carnian and include early sauropodomorphs and theropods. Most Triassic dinosaurs were small predators and only a few were common, such as Coelophysis, which was 1 to 2 metres (3.3 to 6.6 ft) long. Triassic sauropodomorphs primarily inhabited cooler regions of the world.

The large predator Smok was most likely also an archosaur, but it is uncertain if it was a primitive dinosaur or a pseudosuchian.

Pseudosuchians were far more ecologically dominant in the Triassic, including large herbivores (such as aetosaurs), large carnivores ("rauisuchians"), and the first crocodylomorphs ("sphenosuchians"). Aetosaurs were heavily-armored reptiles that were common during the last 30 million years of the Late Triassic until they died out at the Triassic-Jurassic extinction. Most aetosaurs were herbivorous and fed on low-growing plants, but some may have eaten meat. "rauisuchians" (formally known as paracrocodylomorphs) were the keystone predators of most Triassic terrestrial ecosystems. Over 25 species have been found, including giant quadrupedal hunters, sleek bipedal omnivores, and lumbering beasts with deep sails on their backs. They probably occupied the large-predator niche later filled by theropods. "Rauisuchians" were ancestral to small, lightly-built crocodylomorphs, the only pseudosuchians which survived into the Jurassic.

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  Tanystropheus, a long-necked tanystropheid

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  Proterosuchus, a crocodile-like early archosauriform from the Early Triassic

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  Staurikosaurus, one of the earliest dinosaurs, a member of the Triassic family Herrerasauridae

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  Postosuchus, a rauisuchid which was an apex predator in parts of Late Triassic North America

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  Plateosaurus was one of the largest of early sauropodomorphs, or "prosauropods", of the Late Triassic

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  Coelophysis was one of the most abundant theropod dinosaurs in the Late Triassic

Marine reptiles

Marine vertebrate apex predators of the Early Triassic and Anisian (Middle Triassic)

There were many types of marine reptiles. These included the Sauropterygia, which featured pachypleurosaurus and nothosaurs (both common during the Middle Triassic, especially in the Tethys region), placodonts, the earliest known herbivorous marine reptile Atopodentatus, and the first plesiosaurs. The first of the lizardlike Thalattosauria (askeptosaurs) and the highly successful ichthyosaurs, which appeared in Early Triassic seas soon diversified, and some eventually developed to huge size during the Late Triassic.

Other reptiles

Among other reptiles, the earliest turtles, like Proganochelys and Proterochersis, appeared during the Norian Age (Stage) of the Late Triassic Period. The Lepidosauromorpha, specifically the Sphenodontia, are first found in the fossil record of the earlier Carnian Age, though the earliest lepidosauromorphs likely occurred in the Permian. The Procolophonidae, the last surviving parareptiles, were an important group of small lizard-like herbivores. The drepanosaurs were a clade of unusual, chameleon-like arboreal reptiles with birdlike heads and specialised claws.

Synapsids

Three therapsid groups survived into the Triassic: dicynodonts, therocephalians, and cynodonts. The cynodont Cynognathus was a characteristic top predator in the Olenekian and Anisian of Gondwana. Both kannemeyeriiform dicynodonts and gomphodont cynodonts remained important herbivores during much of the period. Therocephalians included both large predators (Moschorhinus) and herbivorous forms (bauriids) until their extinction midway through the period. Ecteniniid cynodonts played a role as large-sized, cursorial predators in the Late Triassic. During the Carnian (early part of the Late Triassic), some advanced cynodonts gave rise to the first mammals.

During the Triassic, archosaurs displaced therapsids as the largest and most ecologically prolific terrestrial amniotes. This "Triassic Takeover" may have contributed to the evolution of mammals by forcing the surviving therapsids and their mammaliaform successors to live as small, mainly nocturnal insectivores. Nocturnal life may have forced the mammaliaforms to develop fur and a higher metabolic rate.

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  Lystrosaurus was a widespread dicynodont and the most common land vertebrate during the Early Triassic, after animal life had been greatly diminished

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  Cynognathus was a carnivorous mammal-like cynodont from the Early Triassic.

Lagerstätten

The Monte San Giorgio lagerstätte, now in the Lake Lugano region of northern Italy and Switzerland, was in Triassic times a lagoon behind reefs with an anoxic bottom layer, so there were no scavengers and little turbulence to disturb fossilization, a situation that can be compared to the better-known Jurassic Solnhofen Limestone lagerstätte.

The remains of fish and various marine reptiles (including the common pachypleurosaur Neusticosaurus, and the bizarre long-necked archosauromorph Tanystropheus), along with some terrestrial forms like Ticinosuchus and Macrocnemus, have been recovered from this locality. All these fossils date from the Anisian/Ladinian transition (about 237 million years ago).

Triassic–Jurassic extinction event

Main article: Triassic–Jurassic extinction event

The mass extinction event is marked by 'End Tr'

The Triassic Period ended with a mass extinction, which was particularly severe in the oceans; the conodonts disappeared, as did all the marine reptiles except ichthyosaurs and plesiosaurs. Invertebrates like brachiopods and molluscs (such as gastropods) were severely affected. In the oceans, 22% of marine families and possibly about half of marine genera went missing.

Though the end-Triassic extinction event was not equally devastating in all terrestrial ecosystems, several important clades of crurotarsans (large archosaurian reptiles previously grouped together as the thecodonts) disappeared, as did most of the large labyrinthodont amphibians, groups of small reptiles, and most synapsids. Some of the early, primitive dinosaurs also became extinct, but more adaptive ones survived to evolve into the Jurassic. Surviving plants that went on to dominate the Mesozoic world included modern conifers and cycadeoids.

The cause of the Late Triassic extinction is uncertain. It was accompanied by huge volcanic eruptions that occurred as the supercontinent Pangaea began to break apart about 202 to 191 million years ago (40Ar/39Ar dates), forming the Central Atlantic Magmatic Province (CAMP), one of the largest known inland volcanic events since the planet had first cooled and stabilized. Other possible but less likely causes for the extinction events include global cooling or even a bolide impact, for which an impact crater containing Manicouagan Reservoir in Quebec, Canada, has been singled out. However, the Manicouagan impact melt has been dated to 214±1 Mya. The date of the Triassic-Jurassic boundary has also been more accurately fixed recently, at 201.4 Mya. Both dates are gaining accuracy by using more accurate forms of radiometric dating, in particular the decay of uranium to lead in zircons formed at time of the impact. So, the evidence suggests the Manicouagan impact preceded the end of the Triassic by approximately 10±2 Ma. It could not therefore be the immediate cause of the observed mass extinction.

Skull of a Triassic Period phytosaur found in the Petrified Forest National Park

The number of Late Triassic extinctions is disputed. Some studies suggest that there are at least two periods of extinction towards the end of the Triassic, separated by 12 to 17 million years. But arguing against this is a recent study of North American faunas. In the Petrified Forest of northeast Arizona there is a unique sequence of late Carnian-early Norian terrestrial sediments. An analysis in 2002 found no significant change in the paleoenvironment. Phytosaurs, the most common fossils there, experienced a change-over only at the genus level, and the number of species remained the same. Some aetosaurs, the next most common tetrapods, and early dinosaurs, passed through unchanged. However, both phytosaurs and aetosaurs were among the groups of archosaur reptiles completely wiped out by the end-Triassic extinction event.

It seems likely then that there was some sort of end-Carnian extinction, when several herbivorous archosauromorph groups died out, while the large herbivorous therapsids—the kannemeyeriid dicynodonts and the traversodont cynodonts—were much reduced in the northern half of Pangaea (Laurasia).

These extinctions within the Triassic and at its end allowed the dinosaurs to expand into many niches that had become unoccupied. Dinosaurs became increasingly dominant, abundant and diverse, and remained that way for the next 150 million years. The true "Age of Dinosaurs" is during the following Jurassic and Cretaceous periods, rather than the Triassic.