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80 / Paleozoic
Pikaia
Pikaia gracilens
A slender body preserves repeated muscle blocks and internal traces important for interpreting early chordates.
Structured expansion · editorial review pending
- Time range
- About 508 million years ago
- Final stage
- Middle Cambrian
- Geographic range
- Laurentian shallows · Present-day Canada
01 / ANSWER FIRST
What was Pikaia?
This archive records Pikaia under the scientific name Pikaia gracilens, with an age of About 508 million years ago and a range of Laurentian shallows · Present-day Canada. A slender body preserves repeated muscle blocks and internal traces important for interpreting early chordates.
Pikaia undulated above the Cambrian seafloor. It was not our direct ancestor, but its body organization illuminates the early history of chordates.
02 / QUICK FACTS
Pikaia at a glance
- Scientific name
- Pikaia gracilens
- Age
- About 508 million years ago
- Last recorded stage
- Middle Cambrian
- Known range
- Laurentian shallows · Present-day Canada
- Broad group
- invertebrate
- Archive era
- Paleozoic
- Habitat signals
- Ocean
- Documented regions
- North America
03 / ANATOMY
How was Pikaia built?
Overall body plan
A slender body preserves repeated muscle blocks and internal traces important for interpreting early chordates.
Body symmetry and segmentation
The available record is interpreted through preserved proportions, attachment surfaces, wear and comparison with related organisms. For Pikaia, those observations must be separated from features added only for visual reconstruction.
Feeding and locomotor structures
Pikaia undulated above the Cambrian seafloor. It was not our direct ancestor, but its body organization illuminates the early history of chordates.
Growth and individual variation
A single specimen does not define the whole species. Size, maturity, preservation and possible sex differences are considered before anatomical traits are treated as typical of Pikaia.
04 / DIET & BEHAVIOUR
How did Pikaia live?
Pikaia undulated above the Cambrian seafloor. It was not our direct ancestor, but its body organization illuminates the early history of chordates. This ecological reconstruction is strongest where anatomy, associated organisms and the depositional setting point in the same direction.
05 / DIET & BEHAVIOUR
What shaped its ecological limits?
Its populations depended on substrate, water chemistry, food supply and ecological competition. Changes in any one factor did not necessarily cause immediate extinction, but interacting pressures could reduce range, recruitment and resilience.
06 / RANGE & HABITAT
Where and when did Pikaia live?
This archive currently lists About 508 million years ago; Laurentian shallows · Present-day Canada. Fossil or historical occurrence data describe where evidence has been found, not every place the taxon once occupied. Species-level age and range limits still require source-specific review.
Documented geographic range
Laurentian shallows · Present-day Canada. This boundary can change when specimens are reidentified or new localities are published.
Time window
About 508 million years ago, with the final recorded stage listed as Middle Cambrian. Rock units and dating uncertainty mean the true biological range may extend beyond the known record.
Environmental setting
The archive uses the broad habitat labels Ocean. These labels help explore related records; a habitat reconstruction requires evidence from individual localities.
07 / FOSSIL EVIDENCE
What evidence supports reconstructions of Pikaia?
Primary record
Burgess Shale fossils preserve muscle segments and internal traces. A 2024 study proposed that earlier reconstructions were upside down and reidentified the gut and dorsal nerve cord; these traces should not simply be described as a confirmed dorsal support.
Comparative anatomy
Preserved structures are compared with close and functionally similar organisms. The method can constrain posture and function, but analogy alone cannot prove colour, behaviour or soft tissue.
Age and locality
Stratigraphy and occurrence records place Pikaia within About 508 million years ago and Laurentian shallows · Present-day Canada. Reworked fossils and uncertain provenance are treated cautiously.
Open entity records
Links below connect the archive to available taxonomic and occurrence records. A matching name does not verify every ecological claim, and related-taxon links provide comparison rather than an exact species match.
Evidence limits for this record
The 2024 anatomical reinterpretation reverses the earlier orientation and identifies a dorsal nerve cord. It supports a stem-chordate interpretation without making Pikaia a demonstrated direct ancestor of living vertebrates.
08 / DISAPPEARANCE & DEBATE
Why did Pikaia disappear?
Its limited fossil record does not establish a direct extinction cause.
The last fossil or observation marks the youngest evidence currently known, not necessarily the death of the final individual. Explanations are strongest when timing, environmental change and population biology agree; otherwise the profile preserves uncertainty instead of assigning a single dramatic cause.
09 / FREQUENTLY ASKED QUESTIONS
Pikaia FAQ
What was Pikaia?
This archive records Pikaia under the scientific name Pikaia gracilens, with an age of About 508 million years ago. A slender body preserves repeated muscle blocks and internal traces important for interpreting early chordates.
When did Pikaia live?
The current archive range is About 508 million years ago; its youngest recorded stage is Middle Cambrian.
Where was Pikaia found?
The archive currently lists Laurentian shallows · Present-day Canada. Species-level locality assignments and the full geographic range still require source-specific review.
How do scientists know about Pikaia?
Burgess Shale fossils preserve muscle segments and internal traces. A 2024 study proposed that earlier reconstructions were upside down and reidentified the gut and dorsal nerve cord; these traces should not simply be described as a confirmed dorsal support.
04 / SOURCES & FURTHER READING
Check the source record
Use the scientific name to compare taxonomy, occurrence records and the fossil record. Database coverage and classifications may differ.
05 / REVISION HISTORY
How has this record changed?
- Completed an AI-assisted bilingual audit of the archive record, corrected identified issues and clarified evidence limits; independent editorial review is pending.
- Expanded into a structured bilingual profile with anatomy, ecology, range, evidence, debate and FAQs; independent editorial review is pending.
- Verified authoritative entity sources and added three responsive reconstruction sizes.
- Initial bilingual species record published.
06 / CORRECTIONS & ADDITIONS