Louis Dollo

Louis Antoine Marie Joseph Dollo (Lille, 7 December 1857 – Brussels, 19 April 1931) was a Belgian palaeontologist, known for his work on dinosaurs. He also posited that evolution is not reversible, known as Dollo's law. Together with the Austrian Othenio Abel, Dollo established the principles of paleobiology.

Louis Dollo
Louis Dollo 2
Louis Dollo
Born7 December 1857
Died19 April 1931 (aged 73)
Known forDollo's law
AwardsMurchison Medal (1912)
Scientific career

Early life

Louis Dollo was born in Lille, Nord-Pas-de-Calais, a scion of an old Breton family. He studied at the École Centrale de Lille, with geologist Jules Gosselet and zoologist Alfred Giard, both of whom influenced the young Dollo.[1] In 1877, he graduated with a degree in engineering. After his graduation, he worked in the mining industry for five years, but simultaneously developed a passion for paleontology. In 1879, he moved to Brussels.

Iguanodon spp.

For three years, starting in 1878, he supervised the excavation of the famous, multiple Iguanodon find at Bernissart, Belgium. He devoted himself to their study as a scientific passion, initially concurrently with his engineering career.[2] In 1882 he became an assistant naturalist at the Royal Belgian Institute of Natural Sciences. Dollo was given membership in the Société des sciences de Lille and the Geological Society of London.

From 1882 to 1885, while he was head of the vertebrate fossil section of the Royal Institute, Dollo worked on reconstructing the skeletons of the iguanodons, as it was necessary to display them on their hind legs. The first one was assembled in the interior of an unused church that Dollo was using as a workshop. Twelve of those skeletons have been the principal attraction of the Museum of Natural Sciences at the Royal Institute. Dollo collaborated with his former professor Alfred Giard and the Université Lille Nord de France.

Dollo's law

Around 1890, he formulated a hypothesis on the irreversible nature of evolution, known later as "Dollo's law".[3] According to his hypothesis, a structure or organ lost during the course of evolution would not reappear in that organism. This hypothesis was largely accepted until Michael F. Whiting's 2003 discovery that certain insects that had lost their wings regained them millions of years later.[4] However, it was redeemed on the molecular level in 2009 as a result of a study on glucocorticoid receptors.[5]


Dollo continued his work with fossils, in addition to studies of dinosaurs and their ecology. He was among the first to see fossil animals as part of an ecosystem. Because of that, he was instrumental in the development of paleobiology, and he kept up an extensive correspondence with Othenio Abel, another famous early paleobiologist.

He taught paleontology at the Free University of Brussels, beginning in 1909, and in 1912 received the Murchison Medal. Recently, the stochastic Dollo model is being used to analyze matrix of cognates statistically. In linguistics, this model permits a newly coined cognate to arise only once on a tree language.


Animal classifications


  • Louis Dollo (1882), "Première note sur les dinosauriens de Bernissart". Bulletin du Musée Royal d'Histoire Naturelle de Belgique 1: 161–180.
  • Louis Dollo (1883), "Note sur les restes de dinosauriens rencontrés dans le Crétacé Supérieur de la Belgique". Bulletin du Musée Royal d'Histoire Naturelle de Belgique 2: 205–221.
  • Louis Dollo (1891), "La vie au sein des mers : la faune marine et les grandes profondeurs, les grandes explorations sous marines, les conditions d'existence dans les abysses, la faune abyssale, in: Bibliothèque scientifique contemporaine.
  • Louis Dollo (1892), "Sur le "Lepidosteus suessoniensis", in: Bulletin scientifique de la France et de la Belgique.
  • Louis Dollo (1892), "Sur la morphologie des côtes", in: Bulletin scientifique de la France et de la Belgique.
  • Louis Dollo (1892), "Sur la morphologie de la colonne vertébrale", in: Bulletin scientifique de la France et de la Belgique.
  • Louis Dollo (1899), "Première note sur les mosasauriens de Maestricht", Bulletine. Soc. belge Geol. Pal. Hydr., Vol.4.
  • Louis Dollo (1899), Alfred Giard, "Les ancêtres des Marsupiaux étaient-ils arboricoles ?", Station Zoologique de Wimereux.
  • Louis Dollo (1903), "Les Ancêtres des mosasauriens", in: Bulletin scientifique de la France et de la Belgique.
  • Louis Dollo (1904), Expédition antarctique belge (1897–1899) ; résultats du voyage du S. Y. Belgica en 1897 – 1898 – 1899 sous le commandement de A. de Gerlache de Gomery; rapports scientifiques : Zoologie : Poissons. Antwerp: J.-E. Buschmann.
  • Louis Dollo (1905), "Les Dinosauriens adaptés à la vie quadrupède secondaire." Bulletine. Soc. belge Geol. Pal. Hydr., 19: 441–448.
  • Louis Dollo (1910), La Paléontologie éthologique.
Translations by Louis Dollo
  • John Tyndall, Les Microbes (1882)
  • Rudolf Hörnes, Manuel de paléontologie (1886)
  • Wilhelm Krause, Manuel d'anatomie humaine (1887–89)
Re-published works by Louis Dollo
  • Stephen Jay Gould (1970), "Dollo on Dollo's Law: Irreversibility and the Status of Evolutionary Laws", Journal of the History of Biology / 3, No.2:189–212.
  • Stephen Jay Gould, ed. (1980), Louis Dollo's papers on paleontology and evolution, Original Anthology, New York, Arno Press, 1980
  • David B. Weishampel and Nadine M. White, eds. (2003) The Dinosaur Papers, Washington: Smithsonian Institution Books.
  • Edward Drinker Cope (1886), "Schlosser on Creodonta and Phenacodus ; Dollo on extinct tortoises", Amer. Naturalist. 20. 965–968.

Biographies of Dollo

  • Othenio Abel, “Louis Dollo. 7 Dezember 1857–19 April 1931. Ein Rückblick und Abschied”, in: Palaeobiologica, 4. 321–344 (1931).
  • Victor Émile van Straelen, Louis Dollo : Notice biographique avec liste bibliographique. Bruxelles (1933).
  • N. N. Yakovlev, “Memoirs about Louis Dollo,” Ezhegodn. Vsesoyuzn. Paleontol. O-va 10, 4–9 (1935).
  • P. Brien, “Notice sur Louis Dollo,” Ann. Acad. R. Belg. Not. Biograph. 1, 69–138 (1951).
  • L. Sh. Davitashvili, “Louis Dollo,” in Questions of the History of Sciences and Engineering, Vol. 3. pp. 103–108 (Moscow, 1957) [in Russian].
  • N. N. Yakovlev, Memoirs of a Geologist Paleontologist (Nauka, Moscow, 1965) [in Russian].
  • L. K. Gabunia, “Dollo Louis Antone Marie Joseph,” in Dictionary of Scientific Biography (New York), Vol. 4, pp. 147–148 (1971)
  • L. K. Gabunia, Louis Dollo (1857–1931) (Nauka, Moscow, 1974) [in Russian].
  • Yu. Ya. Soloviev, Louis Dollo, Paleontologicheskii Zhurnal, 2008, No. 6, pp. 103–107 [in Russian].
  • Yu. Ya. Soloviev, 150th Anniversary of the birth of Louis Dollo (1857–1931), Paleontological Journal Volume 42, Issue 6, pp 681–684, October 2008.


  1. ^ Othenio Abel (1931), “Louis Dollo. 7 Dezember 1857–19 April 1931. Ein Rückblick und Abschied”, in: Palaeobiologica, 4. 321–344.
  2. ^ Dollo, Louis. “Le Centenaire des Iguanodons (1822–1922).”, in: Philosophical Transactions of the Royal Society of London. Series B, Containing Papers of a Biological Character 212 (1924): 67–78, 2 pl.
  3. ^ Dollo, Louis. Les Lois De L'évolution. New York: Arno, 1893.
  4. ^ Michael F. Whiting, Sven Bradler & Taylor Maxwell, "Loss and recovery of wings in stick insects", in: Nature 421, 264–267 (16 January 2003)
  5. ^ Pagel, Mark (2009). "Human language as a culturally transmitted replicator"in: Nature Reviews Genetics (Macmillan Publishers Limited.) 10 (6): 405–15. doi:10.1038/nrg2560 . PMID 19421237.

Aachenosaurus is a dubious genus of prehistoric plant. It was named based solely on fossilized fragments of material that were originally thought to be jaw fragments from a duck-billed dinosaur (a hadrosaur). However, the fossils turned out to be petrified wood, to the great embarrassment of the discoverer. The fossil's name means "Aachen lizard", named for the Aachenian deposits of Moresnet (which was a neutral territory between Belgium and Germany), where the fossils were found.A synonym of Aachenosaurus is Aachenoxylon, which was coined by Dr Maurice Hovelacque in 1889/1890.


Bernissart is a Walloon municipality located in the Belgian province of Hainaut. On January 1, 2006, Bernissart had a total population of 11,458. The total area is 43.42 km², which gives a population density of 264 inhabitants per km². The municipality includes the village of Blaton, formerly an independent municipality.


Bernissartia ('of Bernissart') is an extinct genus of neosuchian crocodyliform that lived in the Early Cretaceous, around 130 million years ago.

At only 60 centimetres (2.0 ft) in length, Bernissartia is one of the smallest crocodyliforms that ever lived. It resembled modern species in many respects, and was probably semi-aquatic. It had long, pointed teeth at the front of the jaws that would have been of use in catching fish, but broad and flat teeth at the back of its jaws that were suited for crushing hard food, such as shellfish, and possibly bones.It is known primarily from skulls and skeletons found in modern-day Belgium and Spain. Less complete material has been referred to Bernissartia from the United Kingdom and North America.


Boulengerina is a genus or subgenus of elapid snakes known commonly as water cobras, so named because of their semiaquatic nature. The genus was recognised to have two species, which are found in central and southern Africa. Some recent molecular studies have suggested that the genus Boulengerina should be synonymised with Naja, because the water cobras are closely related to some species of Naja.Wallach, Wüster and Broadley, re-ranked Boulengerina as a subgenus within Naja comprising the two species already recognised as forming genus Boulengerina plus Naja melanoleuca, as Naja (Boulengerina) melanoleuca, and the species formerly known as Paranaja multifasciata, now Naja (Boulengerina) multifasciata.


Carinodens is an extinct genus of Cretaceous marine lizard belonging to the mosasaur family. "Carinodens" means "keel teeth" and was named in 1969 as a replacement name for Compressidens, "compressed teeth", which was already in use for a gadilidan scaphopod mollusk.Carinodens is widely considered a sister taxon to Globidens classified within the tribe Globidensini. Like its close relative, Carinodens also possesses distinctive round, blunt teeth for crushing primitive clams and oysters. Most of the cranial elements known from the genus have been recovered from deposits in the Netherlands, with the only known postcranial material being known from deposits of latest Maastrichtian age in Jordan.


Craspedodon (meaning 'edge tooth') is an extinct genus of ornithischian dinosaur, possibly a ceratopsian. It lived during the Late Cretaceous (Santonian stage, around 85 million years ago), in what is now Belgium. Only a few teeth have ever been found, which were described as similar to those of Iguanodon. Craspedodon lonzeensis, described by Louis Dollo in 1883, is the type species, although it is considered a nomen dubium since it is based on fragmentary material (teeth only). It was long thought to be an iguanodontian, but restudy suggested that it was actually a neoceratopsian, perhaps closer to Ceratopsoidea than Protoceratopsidae. If the reidentification is correct, Craspedodon would be the first neoceratopsian known from Europe.

Cynomacrurus piriei

Cynomacrurus piriei, the dogtooth grenadier, is a species of rattail that occurs in the southern oceans, mostly south of the Antarctic Convergence. This fish is found at depths of from 500 to 3,800 metres (1,600 to 12,500 ft). This species grows to a length of 50 centimetres (20 in) TL.In 1909, Louis Dollo paper describing this species and circumscribing its monospecific genus Cynomacrurus was published. The species's type locality is in the Weddell Sea at 71°50′S 23°30′W. The holotype was collected by the Scotia during the Scottish National Antarctic Expedition on 15 March 1904; it was later deposited in the Scottish Oceanographical Laboratory. The specific epithet was named in honor of Harvey Pirie, who was the surgeon, geologist, and bacteriologist aboard the Scotia.

Devolution (biology)

Devolution, de-evolution, or backward evolution is the notion that species can revert to supposedly more primitive forms over time. The concept relates to the idea that evolution has a purpose (teleology) and is progressive (orthogenesis), for example that feet might be better than hooves or lungs than gills. However, evolutionary biology makes no such assumptions, and natural selection shapes adaptations with no foreknowledge of any kind. It is possible for small changes (such as in the frequency of a single gene) to be reversed by chance or selection, but this is no different from the normal course of evolution.

In the 19th century, when belief in orthogenesis was widespread, zoologists (such as Ray Lankester and Anton Dohrn) and the palaeontologists Alpheus Hyatt and Carl H. Eigenmann advocated the idea of devolution. The concept appears in Kurt Vonnegut's 1985 novel Galápagos, which portrays a society that has evolved backwards to have small brains.

Dollo's law of irreversibility, first stated in 1893 by the palaeontologist Louis Dollo, denies the possibility of devolution. The evolutionary biologist Richard Dawkins explains Dollo's law as being simply a statement about the improbability of evolution's following precisely the same path twice.

Dollo's law of irreversibility

Dollo's law of irreversibility (also known as Dollo's law and Dollo's principle), proposed in 1893 by French-born Belgian paleontologist Louis Dollo states that, "an organism never returns exactly to a former state, even if it finds itself placed in conditions of existence identical to those in which it has previously lived ... it always keeps some trace of the intermediate stages through which it has passed."The statement is often misinterpreted as claiming that evolution is not reversible, or that lost structures and organs cannot reappear in the same form by any process of devolution. According to Richard Dawkins, the law is "really just a statement about the statistical improbability of following exactly the same evolutionary trajectory twice (or, indeed, any particular trajectory), in either direction". Stephen Jay Gould suggested that irreversibility forecloses certain evolutionary pathways once broad forms have emerged: "[For example], once you adopt the ordinary body plan of a reptile, hundreds of options are forever closed, and future possibilities must unfold within the limits of inherited design."This principle is classically applied to morphology, particularly of fossils, but may also be used to describe molecular events, such as individual mutations or gene losses.

Gerard Smets

Gerard Smets (fl. October 31, 1888 – 1890) was a Belgian paleontologist, scientist and abbé known for the misidentification of the plant genus Aachenosaurus, named after the locale of Aachen in Belgium.

Smets was most likely born in or near Brussels, Belgium before 1855.


Hainosaurus (Haino from the river Haine, where it was first discovered, and saurus, from Greek sauros, meaning lizard) is an extinct genus of marine reptiles belonging to the mosasaur family. It is one of the largest mosasaurs, though its size has been revised more than once. At first it was estimated to be 17 metres (56 ft), and the largest mosasaurid. During the 1990s, its size was revised to 15 metres (49 ft) long; more recently, Johan Lindgren estimated that it reached lengths of up to 12.2 metres (40 ft). It was one of the top marine predators of the Late Cretaceous. Like other giant mosasaurs, this giant predator preyed on turtles, plesiosaurs, pterosaurs, cephalopods, sharks, fish, and smaller mosasaurs.

The fossils of H. pembinensis were found in the Upper Cretaceous Pierre Shale in Manitoba, Canada in 1988. It was distinguished from Tylosaurus by having a greater number of vertebrae before the tail, a larger femur to humerus ratio, and larger nostrils. However, a 2008 study found that conclusion to be problematic, and thus reclassified into the genus Tylosaurus as T. pembinensis. Likewise, Hainosaurus neumilleri Martin, 2007 is a nomen dubium within Tylosaurus.

Hainosaurus is a member of the subfamily Tylosaurinae, and it is related to the wholly North American Tylosaurus. However, it has more vertebrae from the neck to the part of the tail with chevrons (53) than Tylosaurus (35). Both genera are large marine superpredators. Hainosaurus' tail has less chevron-bearing vertebrae, making it shorter than that of Tylosaurus. The type species of Hainosaurus is H. bernardi, named after the Belgian Léopold Bernard, owner of the phosphate chalk exploitation where the fossil was unearthed. In a paper published in 2016, Hainosaurus was considered congeneric with Tylosaurus.


Hylaeobatrachus is an extinct genus of prehistoric salamander.


Mantellisaurus is a genus of iguanodontian dinosaur that lived in the Barremian and early Aptian ages of the Early Cretaceous Period of Europe. Its remains are known from Belgium (Bernissart), England and Germany. The type and only species is M. atherfieldensis. Formerly known as Iguanodon atherfieldensis, the new genus Mantellisaurus was erected for the species by Gregory Paul in 2007. According to Paul, Mantellisaurus was more lightly built than Iguanodon and more closely related to Ouranosaurus, making Iguanodon in its traditional sense paraphyletic. It is known from many complete and almost complete skeletons. The genus name honours Gideon Mantell, the discoverer of Iguanodon.

Murchison Medal

The Murchison Medal is an academic award established by Roderick Murchison, who died in 1871. First awarded in 1873, it is normally given to people who have made a significant contribution to geology by means of a substantial body of research and for contributions to 'hard' rock studies. One of the closing public acts of Murchison’s life was the founding of a chair of geology and mineralogy in the University of Edinburgh. Under his will there was established the Murchison Medal and geological fund (The Murchison Fund) to be awarded annually by the council of the Geological Society of London.

Museum of Natural Sciences

The Museum of Natural Sciences of Belgium (French: Muséum des sciences naturelles de Belgique, Dutch: Museum voor Natuurwetenschappen van België) is a museum dedicated to natural history, located in Brussels, Belgium. The museum is a part of the Royal Belgian Institute of Natural Sciences. Its most important pieces are 30 fossilised Iguanodon skeletons, which were discovered in 1878 in Bernissart, Belgium. The dinosaur hall of the museum is the world's largest museum hall completely dedicated to dinosaurs. Another famous piece is the Ishango bone, which was discovered in 1960 by Jean de Heinzelin de Braucourt in the Belgian Congo. The museum also houses a research department and a public exhibit department.

Othenio Abel

Othenio Lothar Franz Anton Louis Abel (Vienna, June 20, 1875 – Mondsee, Upper Austria, July 4, 1946) was an Austrian artist and fossil creator. Together with Louis Dollo, he was the founder of "paleobiology" and studied the life and environment of fossilized organisms.


Phosphorosaurus ("Phosphate Lizard") is an extinct genus of marine lizard belonging to the mosasaur family. Phosphorosaurus is classified within the Halisaurinae subfamily alongside the genera Pluridens, Eonatator and Halisaurus.Stratigraphically, Phosphorosaurus only occurs in the Maastrichtian stage of the Late Cretaceous. Although treated as synonymous with Halisaurus in the past, recent studies recognize it as valid. Two species are known, Phosphorosaurus ortliebi from Belgium, and P. ponpetelegans from Hokkaido in Japan. P. ponpetelegans is only known from the very earliest Maastrichtian, whilst P. ortliebi occurs throughout the Maastrichtian.


Plioplatecarpus is a genus of mosasaur lizard. Like all mosasaurs, it lived in the late Cretaceous period, about 73-68 million years ago.


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