| 21. | If the latter is the case, then aptychi may have had a function similar to the head shield of modern nautiluses.
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| 22. | Like other ostracoderms, " Ateleaspis " had a head shield similar to that of " Cephalaspis ".
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| 23. | In most species, there are two eyes at the front side of the head shield, often merged into a single dorsal eye lobe.
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| 24. | The specimen is over 6 cm long and has a body consisting of a head shield, 11 body tergites, and a terminal plate.
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| 25. | The body and tail is covered in transverse bands of more or less square plate like scales, and head shields are fused to the skull.
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| 26. | The supraoculars are small, and they are bordered medially by a row of small scales, which prevent them from contacting the median head shields.
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| 27. | The head shield overlaps a tapering series of 12 17 trunk tergites, which lead into a set of limb-bearing segments comprising the thorax.
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| 28. | The male body length is, the male pronotum ( head shield ) is, the female body length is, and the female pronotum is.
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| 29. | The anterior head shields are strongly fragmented, but the frontal scale, supraoculars and canthus rostralis " so that it can be seen from above.
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| 30. | The first specimens of " P . doylei " were empty sandstone casts of the head shields, with none of the original bone remaining.
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