| 1. | The skin is densely covered by minute, overlapping dermal denticles.
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| 2. | The maxillary teeth are flattened with denticles on their trailing edges.
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| 3. | The skin is densely covered by small, overlapping dermal denticles.
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| 4. | Both sets of denticles are smooth, monocuspid and curved posteriorly.
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| 5. | The remains of primitive fish include thelodont denticles and acanthodian fragments.
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| 6. | The skin is smooth and soft, entirely lacking dermal denticles.
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| 7. | The skin is completely devoid of dermal denticles even in adults.
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| 8. | There are no enlarged denticles on the base of the tail.
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| 9. | The two species also differ in denticle coverage and meristic counts.
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| 10. | The skin often bears creases and is devoid of dermal denticles.
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