MAMMALS
CATEGORY I - CATEGORY II - CATEGORY III - CATEGORY IV
KEY TO USE OF CATEGORIES
FISHES
CATEGORY A - CATEGORY B - CATEGORY C - CATEGORY D
KEY TO USE OF CATEGORIES
Resolved Extinctions
Category I 

1. Species is valid taxonomically. 

2. Date of last existence (EED) proven to postdate AD 1500 according to one or more of the following: 

(i) specimens collected after AD 1500 

(ii) observation of the species by a reliable source after AD 1500 

(iii) fossil remains radiometrically postdate AD 1500, or are associated with other datable remains. 

3. EED attributed to more than 50 years ago because specimens were not observed by a reliable source, or collected, during the last 50 years despite an attempt to locate the species.
Resolved Extinctions
Category A 

1. Species is valid taxonomically. 

2. Date of last existence (EED) proven to postdate AD 1500 because specimens have been collected after this date (observation of the species without collected samples is not acceptable evidence). 

3. EED attributed to more than 50 years ago because specimens were not collected during the last 50 years.

4. Absence of the species after its EED can be attributed to an extinction, rather than the species simply being overlooked, because of evidence of both of the following: 

(i) appropriate sampling either in a search targeted toward that species or in a sampling exercise that covers the expected range or habitat of that species, 

(ii) a decline of that particular species, or presence of an environmental threat to it, before the EED.

(Criterion #4 was not applied to mammals).

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Unresolved Extinctions 
Category II

Extinction not fully resolved because of one or both of the following: 

1. Species may be invalid taxonomically. 

2. Evidence to confirm the EED as after AD 1500 but more than 50 years ago (see Category I, points 2 and 3) is ambiguous.

Unresolved Extinctions
Category B  (with 3 subcategories)

1. EED proven to postdate AD 1500 because specimens have been collected after this date. 

2. EED attributed to more than 50 years ago because specimens were not collected during the last 50 years. 

3. But the extinction remains unresolved because of ambiguity in one of the following: 

(i) the taxonomy of the species, 

(ii) the evidence that attributes the absence of the species after the EED to its extinction.

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Category III 

1. EED proven to postdate AD 1500 according to one or more of the following: 

(i) specimens collected after AD 1500 

(ii) observation of the species by a reliable source after AD 1500 

(iii) fossil remains radiometrically postdate AD 1500, or are associated with other datable remains. 

2. EED attributed to more than 50 years ago because specimens were not observed by a reliable source, or collected, during the last 50 years despite an attempt to locate the species. 

3. But extinction remains unresolved because the species is not yet taxonomically named and described (for fishes, these species are included with species which are taxonomically invalid).

Category B1

1. Absence of the species after the EED can be attributed to an extinction, rather than the species having been overlooked, because of evidence of one or both of the following: 

(i) appropriate sampling either in a search targeted toward that species or in a sampling exercise that covers the expected range or habitat of that species, 

(ii) a decline of that particular species, or presence of an environmental threat to it, before the EED.

(Criterion #1 was not applied to mammals). 

2. But the extinction remains unresolved because the species is taxonomically invalid or not yet taxonomically named and described. 
Category B2

1. Species is taxonomically valid.

2. The species' absence after the EED may be attributed to its extinction because of evidence of a decline of the species, or presence of an environmental threat to it, before the EED. 

3. But the species' absence after the EED cannot be fully substantiated as an extinction because of insufficient evidence of representative sampling through the species' range and habitat after the EED.

Category B3 

1. Species is taxonomically valid. 

2. The species' absence after the EED may be atrributed to its extinction because representative sampling through the species' range and habitat after the EED failed to produce specimens. 

3. But the species' absence after the EED cannot be fully substantiated as an extinction because of insufficient evidence of a decline of the species, or of an environmental threat to it, before the EED.

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Category IV 

1. Species is taxonomically valid. 

2. EED proven to postdate AD 1500 according to one or more of the following: 

(i) specimens collected after AD 1500 

(ii) observation of the species by a reliable source after AD 1500 

(iii) fossil remains radiometrically postdate AD 1500, or are associated with other datable remains. 

3. The extinction is not fully resolved because the EED falls within the last 50 years; but the EED is substantiated because specimens have not been observed by a reliable source, or collected, following the EED despite an attempt to locate the species.
Category C 

1. Species is taxonomically valid. 

2. EED proven to postdate AD 1500 because specimens have been collected after this date (observation of the species without collected samples is not acceptable evidence). 

3. The extinction is not fully resolved because the EED falls within the last 50 years; but the EED is substantiated because specimens have not been collected following the EED. 

4. Absence of the species after the EED can be attributed to an extinction, rather than the species simply being overlooked, because of evidence of both of the following: 

(i) appropriate sampling either in a search targeted towards that species or in a sampling exercise that covers well the expected range or habitat of that species, 

(ii) a decline of that particular species, or of an environmental threat to it, before the EED. (Criterion #4 was not applied to mammals.)

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Category D (with 3 subcategories)

1. EED proven to postdate AD 1500 because specimens have been collected after this date. 

2. The extinction is not fully resolved because the EED falls within the last 50 years; but the EED is substantiated because specimens have not been collected following the EED. 

3. The extinction remains unresolved also because of ambiguity in one of the following: 

(i) the taxonomy of the species, 

(ii) the evidence that attributes absence of the species after the EED to its extinction.

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Category D1

1. Absence of the species after the EED can be attributed to an extinction, rather than the species having been overlooked, because of evidence of one or both of the following: 

(i) appropriate sampling either in a search targeted towards that species or in a sampling exercise that covers the expected range of that species, 

(ii) a decline of that particular species, or presence of an environmental threat to it, before the EED.  

2. But extinction remains unresolved because the species is taxonomically invalid or not yet taxonomically named and described.
Category D2 

1. Species is taxonomically valid. 

2. The species' absence after the EED may be attributed to its extinction because of evidence of a decline of the species, or of an environmental threat to it, before the EED. 

3. But the species' absence after the EED cannot be fully substantiated as an extinction because of insufficient evidence of representative sampling through the species' range and habitat after the EED.

Category D3 

1. Species is taxonomically valid. 

2. The species' absence after the EED may represent its extinction because representative sampling through the species' range and habitat after the EED failed to produce specimens. 

3. But the species' absence after the EED cannot be fully substantiated as an extinction because of insufficient evidence of a decline of the species, or of an environmental threat to it, before the EED.

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KEY TO USE OF CATEGORIES

1a. EED at least 50 years ago = Go to 2 

1b. EED less than 50 years ago, but supported by evidence of: living specimen seen or collected; fossil remains dateable by radio-carbon techniques or by associated remains of species known to have been introduced post AD 1500 = Category IV

KEY TO USE OF CATEGORIES 

1a. EED at least 50 years ago = Go to 2  

1b. EED less than 50 years ago = Go to 7

2a. Species taxonomically ambiguous (requires review or is not fully described/named) = Go to 3  

2b. Species taxonomically valid and fully described/named = Go to 6

2a. Species taxonomically ambiguous (requires review or not fully described/named) = Go to 3  

2b. Species taxonomically valid and fully described/named = Go to 4

3a. Species described but not taxonomically valid= Go to 4 

3b. Species not taxonomically named and described = Go to 5

3a. EED supported by evidence of: 
1) appropriate but unsuccessful sampling after the EED; and/or, 

2) population decline/environmental threat before the EED = Category B1 

3b. EED without supporting evidence, that is, neither: 
1) appropriate but unsuccessful sampling after the EED; nor 

2) population decline/environmental threat before the EED = Go to 12

4a. Species not taxonomically valid, but EED has supporting evidence to be allocated after 1500 and prior to 50 years ago (supporting evidence includes: living specimen seen or collected; fossil remains dateable by radio-carbon techniques or by associated remains of species known to have been introduced post AD 1500) = Category II 

4b. Species not taxonomically valid and EED without sufficient evidence to be allocated after 1500 and prior to 50 years ago = Category II

4a. EED fully supported by evidence of both: 
1) appropriate but unsuccessful sampling after the EED; and 

2) population decline/environmental threat before the EED = Category A 

4b. EED incompletely supported (insufficient sampling after the EED and/or lack of information on population decline/environmental threat before the EED). = Go to 5
5a. Species not taxonomically named and described but EED has supporting evidence to be allocated after 1500 and prior to 50 years ago (supporting evidence includes: living specimen seen or collected; fossil remains dateable by radio-carbon techniques or by associated remains of species known to have been introduced post AD 1500) = Category III 

5b. Species not taxonomically named and described and EED without sufficient evidence to be allocated to after 1500 and prior to 50 years ago = Category III

5a. EED partially supported by evidence of either: 
1) appropriate but unsuccessful sampling after the EED; or 

2) population decline/environmental threat before the EED = Go to 6 

5b. EED lacking evidence of both: 
1) appropriate but unsuccessful sampling after the EED; and 

2) population decline/environmental threat before the EED = Go to 12

6a. Species taxonomically valid and fully described/named, and EED with supporting evidence to be allocated after 1500 and prior to 50 years ago (supporting evidence includes: living specimen seen or collected; fossil remains dateable by radio-carbon techniques or by associated remains of species known to have been introduced post AD 1500) = Category I 

6b. Species taxonomically valid and fully described/named, but EED without sufficient evidence to be allocated after 1500 and prior to 50 years ago = Category II

6a. EED lacking evidence of appropriate but unsuccessful sampling after the EED, but supported by evidence of population decline/environmental threat before the EED = Category B2 

6b. EED lacking evidence of population decline/environmental threat before the EED, but supported by evidence of appropriate but unsuccessful sampling after the EED = Category B3

7a. Species taxonomically ambiguous (requiring review or not fully described/named) = Go to 8 

7b. Species taxonomically valid and fully described/named = Go to 9  

8a. EED supported by evidence of: 
1) appropriate but unsuccessful sampling after the EED; and/or, 

2) population decline/environmental threat before the EED = Category D1 

8b. EED without supporting evidence, that is, neither: 
1) appropriate but unsuccessful sampling after the EED; nor 

2) population decline/environmental threat before the EED = Go to 12 

9a. EED fully supported by evidence of both: 
1) appropriate but unsuccessful sampling after the EED; and 

2) population decline/environmental threat before the EED = Category C 

9b. EED incompletely supported by evidence (insufficient sampling after the EED and/or lack of information on population decline/environmental threat before the EED) = Go to 10 
10a. EED partially supported by evidence of either: 
1) appropriate but unsuccessful sampling after the EED; or 

2) population decline/environmental threat before the EED = Go to 11 

10b. EED lacking evidence of both: 
1) appropriate but unsuccessful sampling after the EED; and 

2) population decline/environmental threat before the EED = Go to 12 

11a. EED lacking evidence of appropriate but unsuccessful sampling after the EED, but supported by evidence of population decline/environmental threat before the EED = Category D2 

11b. EED lacking evidence of population decline/environmental threat before the EED, but supported by evidence of appropriate but unsuccessful sampling after the EED = Category D3 

12. Species without sufficient evidence to allocate it to an extinction category but it may have some associated information which gives reasonable cause to highlight it for further analysis.
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