Alcide d’Orbigny was a prolific taxonomist and bryozoans were one of the phyla for which he described an enormous number of new species and supraspecific taxa. He was introduced to these colonial invertebrates by his father as early as 1819 when observing living colonies at La Rochelle, and collected further examples of Recent bryozoans during his explorations of South America (1826–1834). This South American collection, comprising 44 new and two existing species, was described between 1841 and 1847. However, d’Orbigny’s main work on bryozoans concerned fossil species and was published between 1850 and 1854 in the
Alcide d’Orbigny fut un taxonomiste extrêmement prolifique. Les Bryozoaires représentent un des embranchements pour lesquels il décrivit un grand nombre des nouveaux taxons du niveau espèce et supérieur. Son père lui fit découvrir ces invertébrés coloniaux dès 1819, par l’observation de colonies vivantes, à La Rochelle. D’Orbigny recueillit d’autres exemples de Bryozoaires actuels pendant ses explorations en Amérique du Sud (1826–1834). La collection sud-Américaine comprend 44 espèces nouvelles et deux déjà nommées, qu’il décrivit entre 1841 et 1847. Néanmoins, les premières œuvres de d’Orbigny concernèrent les Bryozoaires fossiles, lesquels furent décrits entre 1850 et 1854 dans le
Alcide d’Orbigny (1802–1857) was a remarkable naturalist
One of d’Orbigny’s enormous projects was to describe the entire fauna of fossil invertebrates of France and adjoining countries. To this end, he described thousands of species in the
Our interest in d’Orbigny began in connection with the revision of the bryozoan part of the
Bryozoans are colony-forming aquatic invertebrates. Ryland
The individual modules forming a bryozoan colony are known as zooids. Although within a colony the zooids are all genetically identical, they are not necessarily identical in morphology. This is because partitioning of biological functions between zooids often results in zooidal polymorphism. Feeding zooids (autozooids), larval brooding zooids (gonozooids) and defensive zooids (avicularia) are among the variety of polymorphs that occur in bryozoans. Each autozooid has a lophophore consisting of a ring of tentacles surrounding a mouth. Bryozoans are suspension feeders, using cilia on the tentacles to create a current of water that drives food particles (mainly phytoplankton) towards the mouth. The lophophore emerges through an opening, the orifice or aperture, in the frontal surface of the zooidal skeleton. When danger threatens the lophophore can be retracted rapidly into the safety afforded by the tubular or box-shaped zooid. Colonies grow principally by budding new zooids, an asexual process. Sexual reproduction, and also dispersal, is usually accomplished via a short-lived larval stage. After settling on a hard or firm substratum, the larva metamorphoses into the founder zooid (ancestrula) of the colony that then begins budding new zooids. The pattern of zooidal budding is important in determining colony-form, which varies considerably between species and sometimes within a single species. Some bryozoan colonies take the form of thin encrusting sheets or runners or large multilamellar mounds, whereas others grow upright into bushy or mesh-like shapes, and yet others develop cap-shaped, free-living colonies.
There is little overlap taxonomically between the orders of bryozoans that dominated Palaeozoic faunas and those of the post-Palaeozoic. D’Orbigny was mostly concerned with the latter. The great majority of taxa he described belonged to two orders now known as the Cyclostomata and Cheilostomata but termed ‘Centrifuginés’ and ‘Cellulinés’ respectively by d’Orbigny (note that d’Orbigny included some genera belonging to extinct stenolaemate bryozoan orders within the ‘Centrifuginés’). Zooids in the first order are usually tubular zooids whereas those in the second are typically box-shaped. Cyclostomes have an Ordovician to Recent range, cheilostomes Jurassic to Recent although none older than Cretaceous were known until the 1970s. Some of the richest post-Palaeozoic bryozoan localities in the world are to be found in France, and both the Jurassic and Cretaceous of France contain a diversity of bryozoans unrivalled elsewhere for rocks of these ages. D’Orbigny had access to and described fossil bryozoans from such classic French Jurassic localities as Ranville and Luc-sur-Mer (Calvados), and Cretaceous localities, including Le Havre and Fécamp (Seine-Maritime), Le Mans (Sarthe), Rouen and Saintes (Charente Maritime), Villedieu and Tours (Loire), and Meudon (Hauts-de-Seine).
Contemporary bryozoan systematics relies overwhelmingly on skeletal characters. Hence there is no conflict between the taxonomies employed by neontologists and palaeontologists. Both colonial and zooidal characters are utilised, the former tending to be given more emphasis in cyclostomes, the latter in cheilostomes with their greater levels of zooidal complexity and polymorphism. In spite of his grounding in micropalaeontology and observation and description of zooid-level characters in bryozoans, d’Orbigny emphasised colony-level characters when classifying bryozoans. Therefore, his classification of cheilostomes differs from modern schemes more than does his classification of cyclostomes.
The earliest evidence of Alcide d’Orbigny’s contact with bryozoans comes from a letter written by his father Charles d’Orbigny in 1819 which is translated in Heron-Allen
D’Orbigny’s research on bryozoans began in earnest when describing Recent species collected during his exploration of South America. During the last decade of his life, as his interests became focused on systematic palaeontology and stratigraphy, d’Orbigny’s interests in bryozoans turned towards the rich Cretaceous faunas of France. Bryozoans form an appreciable component of the huge collection of Mesozoic and Cainozoic invertebrates that he assembled.
All of d’Orbigny’s research on bryozoans was published in the 13-year period between 1841 and 1854. However, the exact date of publication of individual works, however, is often difficult to establish. This is particularly unfortunate in view of the issues of taxonomic priority raised by his publications. Sometimes the date given on the title page is incorrect. D’Orbigny’s custom of appending the year in which he wrote a taxonomic description to the taxonomic name adds further to the confusion as these dates invariably antedate the year of publication which is when the taxon becomes ‘available’ in a nomenclatural sense.
Much has been written about d’Orbigny’s exploration of South America between 1826 and 1834
D’Orbigny classified the 46 bryozoan species into four families: Cellaridae, Escharidae, Tubuliporidae and Terebriporidae. He used the cheilostome family Cellaridae for species with articulated colonies belonging to both cheilostomes and cyclostomes; Escharidae for non-articulated, lamellar cheilostomes; the cyclostome family Tubuliporidae for non-articulated cyclostomes plus two cheilostomes assigned to
A species described by d’Orbigny from Rio de Janeiro as
This short unillustrated paper in the
Several of the new genera are from the Palaeozoic, including such well-known bryozoans as
The
The
The second problem is that many of d’Orbigny’s bryozoan species names intended for publication in the
This small and neglected paper
Similar to the previous paper in style, this paper
This monumental work
D’Orbigny summarised the stratigraphical distribution of bryozoan genera and species at the end of the
Like the
Another difficulty is raised by uncertainties regarding the dates of publication of the livraisons of text and sets of plates. Sherborn
Early revisions of the
This two-part, unillustrated publication
The second volume
D’Orbigny’s schemes of bryozoan classification evolved during the course of his research. The first livraison of the
D’Orbigny
Of the twelve families included in the ‘Empâtés’ – encrusting, free-living and fixed-erect forms – only one, the ‘Porinidae’, is in current use. The others are based on genera that were subsequently abandoned or are now
The classification of Centrifuginés used by d’Orbigny in the
There is one important respect in which d’Orbigny’s classification of cyclostomes differs from schemes used nowadays. The skeletal structures and shapes of brooding zooids (gonozooids) are today regarded as crucial in the definition of higher taxa of cyclostomes
D’Orbigny’s generic classification of cyclostomes emphasised colony-form. Sometimes this philosophy was applied to such an extent that encrusting colonies with different shapes as a result of growing on different substrates were placed in different genera. Colonies of
The legacy left by d’Orbigny to bryozoology is almost entirely taxonomic – he erected a plethora of species, genera and families of bryozoans, many of which remain in use today. With regard to cyclostome bryozoans (Centrifuginés), a total of about 370 nominal genera can be found in the literature. Of these, Alcide d’Orbigny is the author of approximately 30% (113; omitting an objective junior synonym and a genus now known to be a cheilostome), by a considerable margin the greatest number named by any single taxonomist. A further 13 d’Orbigny species have since been designated as the type species of genera by later authors. While some of d’Orbigny’s cyclostome genera are little known or seldom used (e.g.,
D’Orbigny introduced 75 new cheilostome genera. Following our study, and discarding those for which type species are lost and which may never be properly understood, we regard 40 of these as having current availability. This number represents only 4% of the 1013 genera and subgenera currently compiled for the
While it is reasonable to portray d’Orbigny as a taxonomic splitter who over-emphasised colony-form and paid too much regard to stratigraphical differences, Heron-Allen’s contention 〚7, p. 60〛 that for these reasons his work “was to all intents and purposes ignored by MacCoy, Hagenow and Haime in their later and more authoritative works on the group” surely exaggerates the truth.
D’Orbigny’s taxonomic descriptions were often of a comparable standard to those published by other authors at the time. Furthermore, he developed thoughtful and logical systems of classification that, in some cases, have stood the test of time. His work has, however, caused a great many difficulties for subsequent students of the Bryozoa. Problems arise from: (1) dates of publication which do not coincide with those given on the title pages of the works and in some instances (
The MNHN, Paris is gratefully acknowledged for providing visiting professorships enabling each of us to study bryozoans in the d’Orbigny Collection. Professor Agnès Rage is warmly thanked for her generous help during our visits to Paris, Professor Bernard Métivier for field assistance, and Professor Philippe Taquet for kindly inviting our participation in the d’Orbigny Colloquium.
The common fouling cheilostome bryozoan
Comparisons between d’Orbigny’s illustrations (
Comparaisons entre les illustrations de d’Orbigny (
Comparisons between d’Orbigny’s illustrations (
Comparaisons entre les illustrations de d’Orbigny (
Comparisons between d’Orbigny’s illustrations (
Comparaisons entre les illustrations de d’Orbigny (
Comparisons between d’Orbigny’s illustrations (
Comparaisons entre les illustrations de d’Orbigny (
Bryozoan species diversity through time as understood by d’Orbigny 〚17 (p. 1082)〛. Five of his 27 stages containing especially large numbers of species are labelled.
Diversité stratigraphique des espèces de Bryozoaires telle qu’elle a été comprise par d’Orbigny 〚17 (p. 1082)〛. Cinq de ses 27 étages, contenant un particulièrement grand nombre d’espèces, sont répertoriés.
Classification tabulated by d’Orbigny in the first livraison of the bryozoan volume of the
Tableau de classification de d’Orbigny dans la première livraison du volume sur les Bryozoaires des
Classification of the Order ‘Cellulinés’ (mainly cheilostomes) adopted by d’Orbigny
Classification de l’ordre des Cellulinés (principalement les cheilostomes) adoptée par d’Orbigny
Classification used by d’Orbigny for the Order ‘Centrifuginés’ (mainly cyclostomes) in the bryozoan volume of the
Classification utilisée par d’Orbigny pour l’ordre Centrifuginés (principalement les cyclostomes) dans le volume sur les Bryozoaires des