Ammonite Fossil Portrayed on an Ancient Greek Countermarked Coin

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Ammonites are fossils of an extinct group of Palaeozoic and Mesozoic marine cephalopods distinguished by their planispiral shells. Ancient human communities are known to have collected and engraved ammonite fossils 25 000 years ago (Riek 1934; Lehmann 1981). In spite of the fact that the ancient Greeks (particularly Xenophanes, in a sixth-century BC fragment preserved in Hippolytus; Mayor 2000:281) were the first to infer that fossils were the remains of once living organisms, ammonite fossils themselves were apparently never mentioned in ancient Greek writings (Edwards 1967). This may have been because there were no direct modern analogues (e.g. living cephalopods with coiled shells) directly available to the ancient Greeks, thus complicating the interpretation of these fossils as the remains of once living creatures. It should be noted, however, that a third-century Greek poet (pseudonym Orpheus) referred to ophites as a vocal stone in which 'dwells a soul, round, roughly black, hard; all over its circumference run sinews, similar to wrinkles." The oracular properties of this stone required the seer to keep a fast, bath the stone in running water, wrap it up like an infant, put it in a shrine, and invoke it by the chanting of spells. With such activation the ophite served as protection from impotence, barrenness, serpent bites and also could cure blindness (Oaldey 1965a; 1965b). Earlier representations of the planispiral form (e.g. Mesolithic rock art in south-eastern Spain, Oaldey 1965a, 1965b; carving on reindeer horn, France, 15 000 BC, Feliks 1998) are less convincingly related to ammonite fossils.

A countermarked coin described here provides evidence that ancient Greeks created artistic portrayals of ammonite fossils, although they probably valued them more for their religious significance rather than for their significance for the study of natural history. The host coin (Figure 1) is composed of bronze or other base metal (weight = 6.816g), and is 20mm in diameter at its widest point. The obverse is in very good to fine condition and shows a diademed male head facing right. The reverse of the coin is largely obliterated, partly by extended wear and/or a weak strike and partly by flattening due to the impact of the relatively large countermark that was applied to the obverse. The coin is in a private collection and has been listed by Mark McMenamin at the Mount Holyoke College Museum of Art.



The countermark (Figure 2), 8.5mm in diameter, is in very fine condition and shows a serially partitioned spiral pattern. The spiral makes approximately two revolutions. The partition lines are either perpendicular to the edge of the spiral or slightly inclined to it. The countermark pattern was apparently intended to portray the cornua ammonis or Ammon's horns. These fossils were referred to by Pliny the Elder (c. AD 77) in his Natural History (37.167): 'Cornua ammonis or horn of Ammon, one of the most sacred stones of Ethiopia, has a golden yellow colour and a shape resembling that of the horn of a ram.' Pliny's reference to a golden yellow colour identifies the fossils he was observing as preserved as calcitic casts and moulds, which typically manifest a honey-yellow colour in the calcitic infillings. Mayor (2000: 275) inferred that the fossils referred to by Pliny were iridescent ammonite fossils. The fact that the identification of ammonite fossils with the horns of Ammon was known to Roman artists is suggested by the portrayal of Zeus Ammon in Figure 3.

Pliny may also have made reference to ammonite fossils in his description (Natural History 11.36) of rocks from Egypt's Eastern Desert. Pliny called rocks with markings resembling snakes ophites. More specifically, his Augustean ophites were rocks with markings that 'curl over like waves so as to form coils.' Harrell (1995) interprets Augustean ophites as saussuritised gabbros from the Roman quarry at Wadi Semna, but a better interpretation of Augustean ophites is as fossil ammonites. …