Geology Biostratigraphy Last Appearance Datum Calculator
Actual section-positive-up known last fossil occurrence height, unknowns retained. Sampling incompleteness, reworking, erosion, stratigraphic direction and chronological interpretation external; not true extinction age.
Description
A last-appearance datum is the highest independently known occurrence in an adopted upward section coordinate.
A last-appearance datum is the highest independently known occurrence in an adopted upward section coordinate.1
An observed endpoint is distinct from proving extinction time. Use this tool to calculate the stated observation or conditional model from supplied measurements.
When to use Geology Biostratigraphy Last Appearance Datum Calculator
Use this tool to calculate the stated observation or conditional model from supplied measurements. Establish the sample and coordinate basis, matching units, calibration source and applicable model assumptions.
How to use Geology Biostratigraphy Last Appearance Datum Calculator and understand its results
- Establish the sample and coordinate basis, matching units, calibration source and applicable model assumptions.
- Enter actualObservedOccurrenceHeightsMeters, occurrenceEvidenceKnownFlags, using the field meanings and rules below, then run the tool.
- Read result.highestKnownLastAppearanceHeightMeters, result.unknownOccurrenceIndices. Interpret each field using the units, signs and evidence rules below.
- If input validation fails, correct the reported field and run again. Before applying a successful result, check the stated reference scope, units, assumptions and any retained unknown evidence.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| actualObservedOccurrenceHeightsMeters | Actual observed occurrence heights meters | list of number | Required |
| occurrenceEvidenceKnownFlags | Occurrence evidence known flags; 1 means known and 0 means unknown; keep the same item order | list of number | Required |
Require nonempty aligned finite occurrence-height and binary known-flag lists with at least one known occurrence. Take the maximum of known heights under an independently adopted upward coordinate and retain zero-based unknown indices. Heights may be negative; no age conversion or extinction inference is made.
highestKnownHeightMeters=max(height_i where known_i=1); unknownIndices={i:known_i=0} Apply the field units and exact ordering, boundary and evidence rules above.
| Output field | Meaning | Value type |
|---|---|---|
| result | Structured result containing the calculation or selected reference fields below | object |
| result.highestKnownLastAppearanceHeightMeters | Maximum known occurrence coordinate in meters on the declared upward axis | number |
| result.unknownOccurrenceIndices | Zero-based positions of occurrences marked unknown | list of number |
{
"input": {
"actualObservedOccurrenceHeightsMeters": [
3,
1,
5
],
"occurrenceEvidenceKnownFlags": [
1,
1,
0
]
},
"output": {
"result": {
"highestKnownLastAppearanceHeightMeters": 3,
"unknownOccurrenceIndices": [
2
]
}
}
}Limitations and assumptions
An observed endpoint is distinct from proving extinction time. Results depend on the independently established measurement basis and the exact model assumptions above.
Every listed input requires an explicit value. Unexpected fields, incorrect value types, nonfinite numbers and sparse numeric arrays fail validation; tool-specific bounds and alignment rules apply as described above. Extremely large inputs or outputs can also be rejected. An input error is distinct from a successful calculation that reports a false comparison or retains unknown evidence.
Alternative or Complementary methods
Use Geology Zircon Age Calculator to examine a related aspect: Zircon age interpretation requires an applicable isotope system and age model.
Use Geology Magnetostratigraphy Reversal Frequency Calculator where its separate inputs and scope apply: A polarity-reversal frequency compares independently identified reversals with a complete recorded interval.
References
Similar or alternative tools
- Geology Zircon Age Calculator
Zircon age interpretation requires an applicable isotope system and age model.
- Geology Magnetostratigraphy Reversal Frequency Calculator
A polarity-reversal frequency compares independently identified reversals with a complete recorded interval.