The early history of ammonite studies in Italy.

Ammonites figured by Aldrovandi on his Musaeum Metallicum.

Since antiquity, ammonites has been associated with myths, legends, religion and even necromancy. You can find reference to these fossils in the works of Emilio Salgari, Sir Walter Scott, Friedrich Schiller and Johann Wolfgang von Goethe.

From the sixteenth to the late eighteenth centuries, the study of ammonites in Italy was crucial in the debate about the real nature of fossil remains. Leonardo describes the ammonites of the Veronese mountains in the code Hammer (formerly Codex Leicester), folio 9, where he identified these fossils as lithified remains of organisms.

Ulisse Aldrovandi describes several specimens of ammonites in his Musaeum Metallicum.  Aldrovandi supported the idea of the inorganic origin of fossils, although he often compared them with existing animals. He recognized some resemblance between ammonites and snakes so he used the term ‘Ophiomorphites’ (or snake-shaped stone).

Ammonites illustration of the Metallotheca Vaticana of Michele Mercati. Two examples of the ammonites described: Calliphylloceras and Phylloceras

In 1574, Michele Mercati organises the famous Metallotheca Vaticana, where describes several ammonites. But he fully embraces the inorganic interpretation of fossils, a real setback with respect to the pioneering hypothesis previously formulated by Leonardo da Vinci. Mercati treats the fossils with he generic term ‘Lapides idiomorphoi’ (stones equipped with proper shape).

In the seventeenth century, the Italian painter Agostino Scilla  compiled an enormous body of evidence, well reasoned and convincing, in favour of the organic nature of fossils found on hills and mountains (Romano, 2014). . However, there is no mention of ammonites is his work. Paolo Silvio Boccone (1633–1704) a Sicilian naturalist and botanist, also supported of the organic nature of fossils. In ‘Recherches et Observations Naturelles’ (1674), he wrote that ammonites – at that time called ‘Corne d’Ammone’ or ‘Corne de Belier’–  represent models (internal) while the original shells of organisms must have  been ‘calcined’ or ‘pulverised’.

Cover of De conchis minus notis and foraminifera of Rimini’s seaside figured by Bianchi (1739, Table I) and attributed by the author to microscopic specimens of ‘Cornu Ammonis’.

In the first half of the eighteenth century, Bartolomeo Beccari began to study tiny shells that could only be observed under the microscope and classified these organisms as microscopic ‘Corni di Ammone’, continuing with the enduring confusion between cephalopods and foraminifera that started in 1565 when Conrad Gesner described the nummulites collected in the surroundings of Paris. Also Giovanni Bianchi (known by the pseudonym Jaco Planco) in his work De conchis minus notis (1739) describes numerous microforaminifera that are found in abundance on the shoreline of Rimini and assigns them the name ‘Corni di Ammone’. This confusion between cephalopods and foraminifera persisted until the French naturalist Alcide d’Orbigny, after 6 years of analysis, arrived to the correct conclusion that these microscopic organisms are a distinct order to which he gave the name of Foraminifera.

References:

Marco Romano, From petrified snakes, through giant ‘foraminifers’, to extinct cephalopods: the early history of ammonite studies in the Italian peninsula, Historical Biology 2014, http://dx.doi.org/10.1080/08912963.2013.879866

Vai, G.B. and Cavazza,W. (Eds) 2003. Four Centuries of the Word Geology, pp. 1–315. Ulisse Aldrovandi 1603 in Bologna. Minerva Edizioni; Bologna.

The legacy of Ulisse Aldrovandi.

Ulisse Aldrovandi (1522-1605).

Ulisse Aldrovandi was born  in Bologna  to a noble family on September 11, 1522. He  studied humanities, law, mathematics, medicine and philosophy at the university of Bologna where became the first professor of natural sciences in 1561. He was arrested for heresy in 1549 and remained in custody or house arrest till he was absolved in April 1550. During this time he coined the term geology and focused on Zoology and Botany.

He is considered one of the foremost biologists of the Renaissance and in 1568 founded the Bologna City Gardens. Monstruorum Historia contains some of the most impressive illustrations of Aldrovandi’s work.

Like da Vinci and Bauhin, some of the most emblematic figures of the Renaissance, Aldrovandi was a pioneer of ichnology. He described several trace fossils in his work Musaeum Metallicum. Like most of Aldrovandi’s works it was published posthumously. The book was entitled originally De Fossilibus but it was changed by Bartolomeo Ambrosini, the book’s editor.

Gastrochaenolites, as figured in Aldrovandi’s Musaeum Metallicum and Gastrochaenolites in a coral. From Wikimedia Commons.

In his Musaeum Metallicum Aldrovandi correctly interpreted bioerosional traces and the corresponding illustration reveals the ichnogenus Gastrochaenolites, a bioerosional trace commonly produced by bivalves. The specimen is presented as “Silicem dactylitem” and is described as a rock presenting “hollows” of varied diameter. He describes the “hollows” as “resembling the cavities in which some lithophagous bivalves seek shelter”.

a- Cosmorhaphe, described by Aldrovandi as snake-like structure. b. Detail of Cosmorhaphe.

He also  describes Cosmorhaphe as a natural curiosity resembling the sinuous curves of a snake. Unlike da Vinci, Aldrovandi argues for an inorganic origin of traces and believes that are  formed by fluids circulating within rocks or natural curiosities -for instance, ammonites are named Ophiomorphites or “snake-shaped stones”- , but he often compares them to existing animals.

Aldrovandi’s Musaeum Metallicum,
1648.

Aldrovandi’s work represents a major step in the history of Ichnology because  includes one of the first examples of a scientific approach to trace fossils and includes some of the earliest artistic representations of invertebrate trace fossils.

References:

Baucon, A. (2010). Leonardo da Vinci, The Founding Fatheer of Ichnology,  PALAIOS, 25 (6), 361-367 DOI: 10.2110/palo.2009.p09-049r

Baucon, A. (2008). Italy, the Cradle of Ichnology: the legacy of Aldrovandi and Leonardo, Studi Trent. Sci. Nat., Acta Geol., 83 (2008): 15-29