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114-524: Mylodon is an extinct genus of ground sloth belonging to the family Mylodontidae , known from southern South America. With a total length of 3 to 4 m and a body mass of 1-2 tonnes, it is one of the largest mylodontids. The oldest finds probably date to the Lower Pleistocene ; however, most of the fossil remains date to the Late Pleistocene . Its distribution ranged from southern Bolivia and

228-557: A species : see Botanical name and Specific name (zoology) . The rules for the scientific names of organisms are laid down in the nomenclature codes , which allow each species a single unique name that, for animals (including protists ), plants (also including algae and fungi ) and prokaryotes ( bacteria and archaea ), is Latin and binomial in form; this contrasts with common or vernacular names , which are non-standardized, can be non-unique, and typically also vary by country and language of usage. Except for viruses ,

342-455: A comparatively small size of the total available chewing surface. In Mylodon , this amounts to a good 1320 mm corresponding to other mylodonts of the same size. The Indian rhinoceros, which is comparable in terms of its dimensions, has, on the other hand, double to four times the value with 2660 to 5190 mm. The situation is similar with the hippopotamus, the total surface area of which is between 3290 and 5410 mm. The small total occlusal surface of

456-413: A comprehensive description. Characteristic of the skull was the narrow snout and a closed nasal arch, which was formed by the firm adhesion of the nasal bone to the middle jaw bone. Furthermore, the dentition consisted of a total of 16 teeth, the upper front canine-like tooth was reduced in each case, in the lower jaw, however, sat four molar-like teeth each. Reinhardt noticed similarities to M. darwinii in

570-454: A dense and thin arrangement of bone platelets to a specific part of the body. However, it can be assumed that the back was largely armored and the stomach was free. In the sections with dense osteoderm formation, these were larger than in the clear areas. The bone platelets of Mylodon were mostly of irregular oval shape with dimensions of 0.5 to 2.5 cm in length, 0.3 to 1.8 cm in width and 0.2 to 1.1 cm in thickness, with weights of

684-438: A kinship proximity to the other large ground sloths known at the time, such as Megatherium or Megalonyx , he placed Glossotherium in a series with the anteaters and with the pangolins , respectively, and postulated an insectivorous lifestyle for the animals. Two years later, however, Owen discarded the name Glossotherium again. This occurred in the course of processing a nearly complete skeleton that had been discovered

798-643: A later homonym of a validly published name is a nomen illegitimum or nom. illeg. ; for a full list refer to the International Code of Nomenclature for algae, fungi, and plants and the work cited above by Hawksworth, 2010. In place of the "valid taxon" in zoology, the nearest equivalent in botany is " correct name " or "current name" which can, again, differ or change with alternative taxonomic treatments or new information that results in previously accepted genera being combined or split. Prokaryote and virus codes of nomenclature also exist which serve as

912-417: A length of about 30 cm. The head was oval in shape with a prominent lip. The pelvis was extremely expansive and 114 cm wide between the two iliac bones. The thigh bone measured between 55 and 59 cm in length. It was typical of ground sloths, being flat in shape. Its width decreased significantly on the shaft, the lowest value was reached just below the midpoint. Here the width was about 18 cm,

1026-621: A long time and redescribed as new by a range of subsequent workers, or if a range of genera previously considered separate taxa have subsequently been consolidated into one. For example, the World Register of Marine Species presently lists 8 genus-level synonyms for the sperm whale genus Physeter Linnaeus, 1758, and 13 for the bivalve genus Pecten O.F. Müller, 1776. Within the same kingdom, one generic name can apply to one genus only. However, many names have been assigned (usually unintentionally) to two or more different genera. For example,

1140-411: A maximum of 2 g. On the surface, they showed individual dimples. In cross-section, they consisted of numerous bundles of fibers mixed with hard bone blades (osteoma). This made their structure much simpler than that of the armadillos, and they probably lacked the keratin layer known from the armadillos. In principle, the osteoderms of Mylodon were similar to those of other large mylodonts. Mylodon

1254-409: A reference for designating currently accepted genus names as opposed to others which may be either reduced to synonymy, or, in the case of prokaryotes, relegated to a status of "names without standing in prokaryotic nomenclature". An available (zoological) or validly published (botanical) name that has been historically applied to a genus but is not regarded as the accepted (current/valid) name for

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1368-464: A row of teeth consisting of a total of four molar-like Teeth. In an extensive 1840 paper, Owen referred the mandible to the new genus he had created, Mylodon, and named the species M. darwinii ( darwinii is the spelling used by Owen, but in modern times darwini is also often used; according to the Regulations of Zoological Nomenclature , the former version is correct.) He related the genus name to

1482-494: A sample of Mylodon dung from Argentina with a note that reads "deposited by Theodore Roosevelt ". Mylodon was a large representative of the Mylodontidae . Its total length was estimated to be around 3 to 4 m. Based on the size of the skull, a weight between 1 and 2 tonnes is assumed, with an approximate estimate of 1.65 tonnes. Thus, Mylodon had about the size of related forms such as Glossotherium or Paramylodon , but

1596-427: A taxon; however, the names published in suppressed works are made unavailable via the relevant Opinion dealing with the work in question. In botany, similar concepts exist but with different labels. The botanical equivalent of zoology's "available name" is a validly published name . An invalidly published name is a nomen invalidum or nom. inval. ; a rejected name is a nomen rejiciendum or nom. rej. ;

1710-455: A total of c. 520,000 published names (including synonyms) as at end 2019, increasing at some 2,500 published generic names per year. "Official" registers of taxon names at all ranks, including genera, exist for a few groups only such as viruses and prokaryotes, while for others there are compendia with no "official" standing such as Index Fungorum for fungi, Index Nominum Algarum and AlgaeBase for algae, Index Nominum Genericorum and

1824-465: Is a distinct genus that was restricted to the Pleistocene of North America. Glossotherium also shares a long history of taxonomic confusion with Mylodon , and currently the only recognized species is Mylodon darwini . At one time, the elephant-sized Megatherium was thought to be closely related, but is recognized as belonging to a separate family ( Megatheriidae ). Below is a phylogenetic tree of

1938-569: Is also supported by the high (hypsodont) tooth crowns and the wide mouth with numerous shapes. The ungulates are mostly used as analogous examples, in which shapes with high tooth crowns and broad-lipped mouths are usually grass-eating, such as various cattle, horses or the white rhinoceros. In contrast, those with low tooth crowns and narrow snouts such as the duiker or the black rhinoceros feed largely selective from various leaves and other soft vegetable foods. In contrast to other large mylodontid sloths such as Glossotherium , Paramylodon or Lestodon ,

2052-460: Is considered a Quaternary extinction wave. In South America, this coincides with the first appearance of humans. Whether the two are causally related is the subject of much controversy. In addition to potential hunting and possible landscape overprinting by early human hunter-gatherer groups, climatic changes may also have had an influence. Numerous archaeological sites, especially in the Pampa region and in

2166-596: Is discouraged by both the International Code of Zoological Nomenclature and the International Code of Nomenclature for algae, fungi, and plants , there are some five thousand such names in use in more than one kingdom. For instance, A list of generic homonyms (with their authorities), including both available (validly published) and selected unavailable names, has been compiled by the Interim Register of Marine and Nonmarine Genera (IRMNG). The type genus forms

2280-498: Is largely unknown in other sloths. In comparison, the skulls of Glossotherium and Lestodon , but also of Paramylodon , showed a nasal area, seen from above, which was rather short and looked clearly cut off when viewed from the side; the roof of the skull was largely straight in Mylodon , only a slight indentation could occur above the orbit. On parietal, significant temporal lines were present, but no head crest formed. The zygomatic arch

2394-453: Is often represented by isolated osteoderms, bones or in the form of coprolites, while human remains are limited to stone artifacts and/or hearths. Whether this also involved a more or less intensive raw material use of sloth bones on the part of humans is in many cases unproven. Numerous bone marks that were originally interpreted as anthropogenically caused are, according to recent studies, due to predation. Evidence of direct hunting by humans of

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2508-611: Is part of a whole system of caves in the region, such as the Cueva del Medio or the Cueva Chica , which line the southern flank of the 556 m high Cerro Benitez like pearls. Cueva del Milodón is a large cave 250 m long, 140 m wide and 30 m high at the entrance and 10 m at the back, respectively. It was discovered in 1895 by the German captain Hermann Eberhard , who also found

2622-460: Is somewhat arbitrary. Although all species within a genus are supposed to be "similar", there are no objective criteria for grouping species into genera. There is much debate among zoologists about whether enormous, species-rich genera should be maintained, as it is extremely difficult to come up with identification keys or even character sets that distinguish all species. Hence, many taxonomists argue in favor of breaking down large genera. For instance,

2736-474: Is the type species , and the generic name is permanently associated with the type specimen of its type species. Should the specimen turn out to be assignable to another genus, the generic name linked to it becomes a junior synonym and the remaining taxa in the former genus need to be reassessed. In zoological usage, taxonomic names, including those of genera, are classified as "available" or "unavailable". Available names are those published in accordance with

2850-408: Is up to 1.5 cm in some places, but it is usually around 1 cm. The skin is densely covered with stiff, slightly wavy hair, with only the top hair being developed, while the undercoat is missing. This feature is similar to the two-toed sloths but less so than the three-toed sloths , which possess an undercoat. The length of the individual hairs vary between 5 and sometimes over 20 cm with

2964-621: The International Code of Zoological Nomenclature ; the earliest such name for any taxon (for example, a genus) should then be selected as the " valid " (i.e., current or accepted) name for the taxon in question. Consequently, there will be more available names than valid names at any point in time; which names are currently in use depending on the judgement of taxonomists in either combining taxa described under multiple names, or splitting taxa which may bring available names previously treated as synonyms back into use. "Unavailable" names in zoology comprise names that either were not published according to

3078-799: The International Plant Names Index for plants in general, and ferns through angiosperms, respectively, and Nomenclator Zoologicus and the Index to Organism Names for zoological names. Totals for both "all names" and estimates for "accepted names" as held in the Interim Register of Marine and Nonmarine Genera (IRMNG) are broken down further in the publication by Rees et al., 2020 cited above. The accepted names estimates are as follows, broken down by kingdom: The cited ranges of uncertainty arise because IRMNG lists "uncertain" names (not researched therein) in addition to known "accepted" names;

3192-490: The Pampas in the north southwards to the southernmost part of Patagonia at around 52 - 53 degrees south, the furthest south of any Pleistocene ground sloth, with some of the best known remains of the species being from the eponymous Cueva del Milodon (cave of Mylodon ) in southern Chile. In addition to skeletal remains, Mylodon is also known from preserved skin and hair. Preserved dung ( coprolites ) indicates that Mylodon

3306-420: The jaguar , Smilodon as a member of the saber-toothed cats , and the giant bear form Arctotherium . Some of the mammal bones have marks that were originally associated with human activity, but the current view is that they are more likely due to predator browsing. In addition to faunal remains, the cave also held a myriad of botanical material. It also yielded one of the most extensive data sequences from

3420-404: The platypus belongs to the genus Ornithorhynchus although George Shaw named it Platypus in 1799 (these two names are thus synonyms ) . However, the name Platypus had already been given to a group of ambrosia beetles by Johann Friedrich Wilhelm Herbst in 1793. A name that means two different things is a homonym . Since beetles and platypuses are both members of the kingdom Animalia,

3534-494: The type species . A different approach was taken by Florentino Ameghino (1854-1911) about ten years later. He confirmed in 1889, the separation of both M. darwinii and M. robustus not only at the species level, but also at the genus level. Deviating from Reinhardt, but agreeing with Owen, he considered the mandible of M. darwinii and the skull fragment of Glossotherium to belong together. Since in this scenario Glossotherium possessed priority over Mylodon (Owen mentioned

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3648-536: The 20th parallel south. Finds reported from Paraguay, however, are considered rather uncertain. The first occurrence of Mylodon may have been in the Lower Pleistocene, but finds are rather rare. During this period, the possibly closely related form Archaeomylodon also occurred in the Pampas region, whose foremost canine teeth of the upper dentition were greatly reduced in size, but not yet completely reduced. Among

3762-451: The Americas, evidence from several sites suggest that they may have hunted Mylodon . The extinction of Mylodon may be the result of climatic change, hunting by Paleoindians, or a combination of both factors. Mylodon was named by Richard Owen on the basis of a nearly complete lower jaw with teeth, which was found by Charles Darwin in a consolidated gravel cliff at Bahía Blanca , during

3876-610: The Argentine province of Buenos Aires. Mainly in the Pampas, there was an overlap in the occurrence of Mylodon with the two other major mylodontid sloth representatives Glossotherium and Lestodon during the Upper Pleistocene. However, actual co-occurrence is rarely attested. These include the important archaeological site of Paso Otero in Buenos Aires Province, the locality of Arroyo de Vizcaíno in southern Uruguay, and

3990-568: The Chuí River. As with many of the other large ground sloths, most of the Mylodon material is from the Upper Pleistocene, with a focus toward the end of the last glacial period. It is also the phase when Mylodon again disappeared from the fossil record. From a global perspective, numerous larger animals became extinct during the transition from the Pleistocene to the Holocene, which is why this event

4104-469: The French botanist Joseph Pitton de Tournefort (1656–1708) is considered "the founder of the modern concept of genera". The scientific name (or the scientific epithet) of a genus is also called the generic name ; in modern style guides and science, it is always capitalised. It plays a fundamental role in binomial nomenclature , the system of naming organisms , where it is combined with the scientific name of

4218-499: The Megatheria with regard to the biting force. The extended mandibular joint allows a wide freedom of movement when chewing. Against this, however, is the zygomatic arch, which is not closed and therefore could only withstand the opposing forces of the masseter and musculus pterygoideus to a limited extent. It can therefore be assumed that forwards and backwards directed chewing movements dominated in Mylodon . The flat tooth crowns lead to

4332-681: The Mylodontidae, based on the work of Boscaini et al. . 2019.   Urumacotherium   Pseudoprepotherium   Paroctodontotherium   Octodontotherium   Brievabradys   Lestodon   Bolivartherium   Thinobadistes   Sphenotherus   Lestobradys   Pleurolestodon   Glossotheridium   Simomylodon   Kiyumylodon   Mylodon   Paramylodon   Glossotherium Recent molecular sequence results obtained using collagen and mitochondrial DNA extracted from fossils indicate that

4446-540: The Pampas, with the Patagonian remains belonging to the separate species Mylodon listai. Mylodon went extinct at the end of the Late Pleistocene-beginning of the Holocene, around 12-10,000 years ago, as part of the end-Pleistocene extinction event , along with other ground sloths and most large animals across the Americas. Mylodon chronologically overlapped with Paleoindians , the first humans to inhabit

4560-419: The Pampas, with the Patagonian remains belonging to the separate species Mylodon listai. The taxonomic history of Mylodon is complex. It has involved confusion and equivocation with other mylodont forms such as Glossotherium and Paramylodon over a long period of time. Some of this complexity can be attributed to the first describer of the genus itself, who is Richard Owen (1804-1892). Owen, one of

4674-608: The Patagonian area, are between 13,500 and 10,000 years old. The majority of these attest to at least a coexistence of humans and ground sloths over an extended period of time. Direct associations of human cultural products and fossil remains of Mylodon are found, among others, at Gruta del Indio in the eastern foothills of the Andes, at Piedra Museo or Las Buitreras, all in Argentina, and at Tres Arroyos in Tierra del Fuego, respectively. Mylodon

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4788-413: The U.S. state of Kentucky , and which Richard Harlan had already described in 1831 under the species assignment Megalonyx laqueatus . Owen, however, recognized similarities in the construction of the mandible to his M. darwinii and renamed Harlan's form. Harlan used an essay two years later to comment on Owen's choice of name regarding Mylodon, which he felt was not very descriptive. According to him,

4902-433: The Upper Pleistocene. Several radiocarbon dates , measured from a wide variety of Mylodon finds, span a period from about 16,700 to 10,200 years ago. The upper data are among the most recent obtained directly from finds of the sloth vertebrate. Mylodon' s close relatives include the ground sloths of the genera Glossotherium and Paramylodon . The latter genus has often been confused with Glossotherium , but Paramylodon

5016-406: The almost equally-proportioned Pyramiodontherium possessing to a 47 cm long shin to a 49 cm long femur. Possibly these differences in the hind leg structure result in much more agile locomotion in the Megatheria in relation to the mylodonts. Similar to other large ground sloths, the hand of Mylodon made contact with the ground with the outer side edge and thus sat up rotated. This is indicated by

5130-462: The angular process does not reach the occlusal plane. The dentition of Mylodon differs greatly from that of the other placental mammals and usually consists of five teeth at the top and four teeth at the bottom per jaw arch, meaning a total of 18 teeth. In the mylodonts, the first tooth was often caniniform while the rear teeth were more molariform . Within the sloth, this structure of the teeth can be called original. A special feature of Mylodon

5244-607: The animal. The samples have since been found to be around 10,000 years old, although they look fresh because of the extreme cold and stable conditions in the caves in which they were found. Well preserved samples of Mylodon remains have been discovered in the Cueva del Milodón site in Patagonia , Chile along the southern flank of Cerro Benítez in the year 1896. Associated with bones of other early Patagonian animals, these remains of Mylodon date from an era earlier than 10,000 BC. The American Museum of Natural History has exhibited

5358-434: The arms were thus angled slightly inwards, which is evident from the position of the olecranon yields. The hands came to rest slightly within the width of the elbow. Such an orientation of the arms can effectively support the large mass of Mylodon . As a result, the hands would also be in a line with the feet, which is also conveyed, among other things, by footprints from Paramylodon . The laterally limited articular surface of

5472-442: The base for higher taxonomic ranks, such as the family name Canidae ("Canids") based on Canis . However, this does not typically ascend more than one or two levels: the order to which dogs and wolves belong is Carnivora ("Carnivores"). The numbers of either accepted, or all published genus names is not known precisely; Rees et al., 2020 estimate that approximately 310,000 accepted names (valid taxa) may exist, out of

5586-483: The body of the lower jaw rose at an angle so that the anterior end of the symphysis was above the occlusal plane of the teeth. As with other sloths, the symphysis extended forward, it ended slightly rounded. According to the rostrum of the skull, Mylodon' s symphysis was narrow and not as wide as in Glossotherium and Lestodon . The mandible foramen opened shortly behind the symphysis. The ascending branch started behind

5700-405: The caves of Última Esperanza give an impression of how they were embedded in the skin and distributed over the body. The bone platelets are all located in the lower section of the skin, while the hairs originate in the upper sections. The distribution turned out to be very inconsistent. Some areas with a dense array of osteoderms contain between 83 and 95 platelets per 10 cm. For others, however,

5814-431: The closest living relatives of Mylodon are the two-toed sloths of genus Choloepus . This revelation came as a surprise, since morphological analyses had previously suggested that two-toed sloths were close to Caribbean sloths and Megalonyx , now regarded as representing two separate and distant branches of the sloth evolutionary tree. Some authors suggest that there were two species, with M. darwini restricted to

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5928-502: The construction of the lower jaw, but in the skull design his find deviated clearly from the broad-nosed M. robustus by the narrow snout. However, according to Reinhardt, there were matches in Owen's Glossotherium skull fragment with corresponding skull sections in M. robustus . Based on the clear parallels between M. darwinii and his narrow-beaked skull finding, Reinhardt propagated the new genus Grypotherium with Grypotherium darwinii as

6042-617: The early and more northerly finds of Mylodon is, for example, a skull from the El Palmar Formation in the Argentine province of Entre Ríos, which dates to the end of the last warm period about 80,000 years ago. Also from the northern distribution areas two partial skeletons are worth mentioning, one of which was found at the Río Anisacate in the Argentine province of Córdoba and the other in Arroyo Quequén Salado near Oriente in

6156-447: The extinct sloths. Possibly this made the stomach of the mylodonts a functional equivalent to the complex stomach of the ruminants, whereby a long passage time of the food enabled efficient digestion, in which even more difficult to access nutrients could be provided, for example from foods with a greater fiber content. Such a digestive system could reduce the amount of processed food in the mouth and thus ultimately also have compensated for

6270-454: The femoral head severely restricted the mobility of the hindlimbs. The same applies to the forearm, the straight spoke with the laterally elongated head of which did not allow any major rotational movements. These features can be interpreted as adaptations to a purely terrestrial lifestyle. Finally, the muscle attachment points on the first cervical vertebra referenced, which are more developed than for example with Paramylodon . Correspondingly,

6384-520: The first skin remains. The great importance of these finds led to the cave, initially known as "Cueva Eberhardt", being subsequently visited and explored by numerous scientists. As a result, a large number of finds accumulated over time, among which Mylodon with bone remains, and numerous coprolites has a large share. Other finds belong to camels such as Lama , horses such as Hippidion or South American ungulates such as Macrauchenia , in addition, several predators are represented, including

6498-561: The food was chopped up. In contrast to the sometimes huge representatives of the Megatheriidae , the joint between the lower jaw and the skull of the Mylodonts was relatively low, roughly at the chewing level of the teeth. The resulting decreasing lever arm of the masseter muscle experiences through the structure of the zygomatic arch, mainly of the descending process, a certain compensation, so that there should have been only minor differences to

6612-446: The form "author, year" in zoology, and "standard abbreviated author name" in botany. Thus in the examples above, the genus Canis would be cited in full as " Canis Linnaeus, 1758" (zoological usage), while Hibiscus , also first established by Linnaeus but in 1753, is simply " Hibiscus L." (botanical usage). Each genus should have a designated type , although in practice there is a backlog of older names without one. In zoology, this

6726-428: The former over the latter in 1840) and Grypotherium, Ameghino introduced the species Glossotherium darwinii. In contrast, he left the status of M. robustus untouched. Arthur Smith Woodward (1864-1944), in turn, followed Reinhardt's reasoning. In a paper published in 1900, he presented findings from ground sloths of southern Patagonia and at the same time revised Charles Darwin's collection. In doing so, he equated

6840-400: The front nasal area between 11.3 and 15.5 cm. The height of the posterior skull was 14.0 to 19.0 cm and the anterior 15.0 to 23.5 cm. The skull was thereby elongated and narrow, unlike Glossotherium and Lestodon that had a short and very broad skull. The extraordinary length of the skull of Mylodon was mainly due to elongations in the rostrum . Seen from above, the rostrum narrowed towards

6954-412: The front. This is where the most important difference to most of the other representatives of the Mylodontidae can be found: The nasal bone was long and narrow and curved downwards in the front area. At the front end, it connected to the middle jawbone, which was lengthened by an appendage, and which in turn fused with the upper jaw. This resulted in a completely closed nasal arch in adult individuals, which

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7068-727: The generic name (or its abbreviated form) still forms the leading portion of the scientific name, for example, Canis lupus lupus for the Eurasian wolf subspecies, or as a botanical example, Hibiscus arnottianus ssp. immaculatus . Also, as visible in the above examples, the Latinised portions of the scientific names of genera and their included species (and infraspecies, where applicable) are, by convention, written in italics . The scientific names of virus species are descriptive, not binomial in form, and may or may not incorporate an indication of their containing genus; for example,

7182-558: The genus Mylodon with two species resulted in the extinct sloth representative being distributed in both South and North America. Owen, in his 1840 work, established the genus Glossotherium in addition to Mylodon , but without designation of a specific species. The basis here was a posterior skull fragment taken from the riverbed of the Arroyo Sarandi in the Uruguay department of Soriano . In contrast to Mylodon , for which Owen assumed

7296-432: The idea that a newly defined genus should fulfill these three criteria to be descriptively useful: Moreover, genera should be composed of phylogenetic units of the same kind as other (analogous) genera. The term "genus" comes from Latin genus , a noun form cognate with gignere ('to bear; to give birth to'). The Swedish taxonomist Carl Linnaeus popularized its use in his 1753 Species Plantarum , but

7410-523: The individuals was associated with about 70 stone objects, whose anthropogenic origin is under discussion. No cut marks are found on the bones as evidence of any human manipulation. The age of the site is given as 11,600 to 10,900 years before present. One of the most important sites is the Cueva del Milodón near Lago Sofía in the Chilean province of Última Esperanza , known mainly for its surviving skin remains. It

7524-405: The large ground sloths is even more difficult. One piece of evidence is often considered to be Quebrada de Quereo, a site on an ancient coastline in northern Chile. From here come, among other things, skeletal remains of two individuals of Mylodon , distributed in each case over a narrowly defined area, but in two different stratigraphic units and at a spatial distance of 21 m from each other. One of

7638-628: The largest component, with 23,236 ± 5,379 accepted genus names, of which 20,845 ± 4,494 are angiosperms (superclass Angiospermae). By comparison, the 2018 annual edition of the Catalogue of Life (estimated >90% complete, for extant species in the main) contains currently 175,363 "accepted" genus names for 1,744,204 living and 59,284 extinct species, also including genus names only (no species) for some groups. The number of species in genera varies considerably among taxonomic groups. For instance, among (non-avian) reptiles , which have about 1180 genera,

7752-421: The last molar and formed an angle of 140° to the occlusal plane. The crown process rose up to 20 cm. In contrast, the articular process was lower, roughly at the level of the occlusal plane, resulting in a low cranial-mandibular connection. The angular process at the rear end of the lower jaw was clearly visible. Sometimes it tipped down and was below the lower edge of the horizontal bone body. The upper side of

7866-515: The lizard genus Anolis has been suggested to be broken down into 8 or so different genera which would bring its ~400 species to smaller, more manageable subsets. Rostrum (anatomy) Rostrum (from Latin rostrum , meaning beak ) is a term used in anatomy for several kinds of hard, beak-like structures projecting out from the head or mouth of an animal. Despite some visual similarity, many of these are phylogenetically unrelated structures in widely varying species. In mammals,

7980-444: The long metacarpal bones of the external digits and the decreasing number of phalanges on them. The special hand position protected the long claws of the inner digits, which did not penetrate the ground while walking. A functionally similar but fundamentally different hand position can be found in the ankle duct of the distantly related present-day great anteater. The elbow joint was pointed slightly outwards when standing on four feet and

8094-413: The lower jaw row a more diamond -shaped outline. The typically more complex bilobed design of the molar-like teeth of Glossotherium and Lestodon , caused by a central constriction, only occurred on the lower rearmost tooth in Mylodon . In general, the rows of teeth diverged to the front, and the teeth were very high crowned ( hypsodont ). The upper row of teeth ranges in length from 10.9 to 13.3 cm,

8208-415: The lower row was between 12.0 and 15.0 cm in length. Postcranial skeletons are far rarer in Mylodon than in the other large mylodontid sloths. As a result, the skeleton is less well documented. Only individual elements of the spine, such as the atlas and various thoracic vertebrae, have been described. The humerus was massive and extremely long at 46 to 48 cm. The joint head, the diameter of which

8322-406: The mandible of M. darwinii with Reinhardt's Grypotherium and subsequently recovered Grypotherium darwinii . Smith Woodward assigned the skull fragment of Glossotherium to M. robustus by analogy with Reinhardt. The mylodontids (particularly Mylodon itself) are often considered to be pronounced grazers because of their dental structure with flat chewing surfaces on the molar-like teeth. This

8436-539: The molar-like teeth (from Greek μυλη ( myle ) for "molar" and ὀδούς ( odoús ) for "tooth", thus translating as much as "molar tooth"), with the species epithet darwinii honoring Darwin as finder of the voucher specimen . As a second species besides M. darwinii Owen referred in his paper to M. harlani . This form was based on a mandible and clavicle, both of which came from the Big Bone Lick in Boone County in

8550-403: The most (>300) have only 1 species, ~360 have between 2 and 4 species, 260 have 5–10 species, ~200 have 11–50 species, and only 27 genera have more than 50 species. However, some insect genera such as the bee genera Lasioglossum and Andrena have over 1000 species each. The largest flowering plant genus, Astragalus , contains over 3,000 species. Which species are assigned to a genus

8664-530: The most important explorers of the Victorian era, was concerned from 1836 with fossil finds brought back by Charles Darwin from his pioneering voyage on HMS Beagle to South America . The collection also included a mandible from Punta Alta near Bahía Blanca in the south of the Argentina Buenos Aires Province (specimen number NHM 16617). The nearly complete specimen was distinguished by

8778-414: The mouth of Mylodon is relatively narrow. A special feature is the closed nasal arch, which is heavily roughened in its front area and thus offers muscle attachment points for a mobile upper lip. Something similar can be said about individual depressions in the vicinity of the infraorbital foramen, which also functioned as starting points for individual muscle strands in the nose and lip area. Maybe Mylodon

8892-447: The name could be applied to almost any extinct mammalian form because almost all of them had the posterior molars. Moreover, the name would be inappropriate because, starting from the Latin version dens molaris for "molar tooth" and the second part of speech don (from dens for "tooth"), there is a duplication that would translate as "molar tooth-tooth". Regardless, Owen's establishment of

9006-428: The name could not be used for both. Johann Friedrich Blumenbach published the replacement name Ornithorhynchus in 1800. However, a genus in one kingdom is allowed to bear a scientific name that is in use as a generic name (or the name of a taxon in another rank) in a kingdom that is governed by a different nomenclature code. Names with the same form but applying to different taxa are called "homonyms". Although this

9120-448: The new species M. robustus. The skull fragment that he had originally placed in Glossotherium he now associated with M. darwinii . As a result of this study, three species of the genus Mylodon already existed in the 1840s. A skull including mandible found at Pergamino in Buenos Aires Province served the Danish zoologist Johannes Theodor Reinhardt (1816-1882) in 1879 as the basis for

9234-417: The number is very thin. However, even with a close arrangement, the osteoderms never unite to form a closed shell, but are always separated from one another by individual skin folds. In accordance with the armadillos' shells, the bone platelets form a single layer and do not appear stacked. Since all skin residues were found isolated from the body skeletons, it is sometimes difficult to assign the skin areas with

9348-498: The occipital joint surfaces are also somewhat further apart. Both can be interpreted as meaning that the more massive skull of Mylodon , caused by the lengthening of the snout region, required greater muscle support. Genus The composition of a genus is determined by taxonomists . The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including

9462-565: The occiput was at about the level of the occlusal plane. When viewed from behind, the occiput appeared almost circular and not as depressed as in Glossotherium and Lestodon . The palate was narrow and was more or less triangularly oriented towards the front of the skull. Numerous small bone openings were characteristic here. The glenoid pit, in which the joint of the lower jaw engages, corresponding to that of other mylodonts with its weak form, but this provided free rotation overall. The lower jaw of Mylodon varied in length between 42 and 48 cm. It

9576-428: The only representatives of the sloths to have bony plates embedded in their skin. Such structures, called osteoderms , are known today to a greater extent only in armadillos. In contrast to the outer armor of the armadillos, the bone platelets of the mylodonts were rather loosely scattered. Hermann Burmeister published the first finds of individual osteoderms of Mylodon as early as the 1860s. The remains of skin found in

9690-414: The original decayed teeth. The flat, flap-like and largely indented structure of the molariform teeth can be emphasized as a characteristic of the mylodonts, which clearly differs from that of the Megatheriidae and Megalonychidae with their two transverse raised ridges per tooth. The shapes of the teeth present in Mylodon were simpler. In the upper jaw row, they had a rather round to oval outline, in

9804-430: The other hand, could only be detected in traces. Accordingly, Mylodon led, at least in southwestern Patagonia, a diet consisting almost exclusively of grasses. The food is reflected in the paleohabitat, as pollen analyzes show that the landscape at that time was tundra-like in character and was therefore almost free of trees with only a few low bushes. Occasional evidence of false beeches is interpreted as pollen carried by

9918-526: The provisions of the ICZN Code, e.g., incorrect original or subsequent spellings, names published only in a thesis, and generic names published after 1930 with no type species indicated. According to "Glossary" section of the zoological Code, suppressed names (per published "Opinions" of the International Commission of Zoological Nomenclature) remain available but cannot be used as the valid name for

10032-454: The region around Cueva del Milodón in southwestern Patagonia are among the southernmost known records of a sloth representative in the Pleistocene. In the Pampa region, the northern limit was found approximately at the Chuí River in the southeastern Brazilian state of Rio Grande do Sul around 30 degrees south latitude. Even more northerly points of discovery, such as Ñuapua in Bolivia, are tangent to

10146-457: The rostrum is that part of the cranium located in front of the zygomatic arches , where it holds the teeth, palate, and nasal cavity. Additionally, the corpus callosum of the human brain has a nerve tract known as the rostrum. The beak or snout of a vertebrate may also be referred to as the rostrum. This Arthropod anatomy-related article is a stub . You can help Misplaced Pages by expanding it . This animal anatomy –related article

10260-433: The shortest in the area of the back of the head, medium-length hair on the back and very long hair on the limbs. Their known color ranges from yellowish to reddish-brown. The hair shafts are uniformly tubular, at the upper end they form blunt tips. As with today's sloths, the hair did not have a pith (medulla). In contrast to the hair of the two-toed sloth, they lack their characteristic longitudinal ribbing. The mylodonts are

10374-473: The small total chewing surface in Mylodon . Direct analysis of the food resources used is possible, among many other things, due to the numerous dung residues in the form of coprolites. These are available not only from the Cueva del Milodón in the Chilean part of Patagonia, but also from other caves. The coprolites of Mylodon have a diameter of up to 18 cm. Investigations of the plant residues showed 80 to 95% grasses and 5 to 20% sedges . Herbaceous plants, on

10488-497: The specific name particular to the wolf. A botanical example would be Hibiscus arnottianus , a particular species of the genus Hibiscus native to Hawaii. The specific name is written in lower-case and may be followed by subspecies names in zoology or a variety of infraspecific names in botany . When the generic name is already known from context, it may be shortened to its initial letter, for example, C. lupus in place of Canis lupus . Where species are further subdivided,

10602-412: The standard format for a species name comprises the generic name, indicating the genus to which the species belongs, followed by the specific epithet, which (within that genus) is unique to the species. For example, the gray wolf 's scientific name is Canis lupus , with Canis ( Latin for 'dog') being the generic name shared by the wolf's close relatives and lupus (Latin for 'wolf') being

10716-418: The survey expedition of HMS Beagle . At several sites, preserved hide and dung have been discovered, and are in such a state of conservation that the people who first discovered them believed they belonged to a living animal, instead of to an extinct species. The discovery of fresh-looking samples of skin and dung sparked a small wave of expeditions during the early 20th century to search for a living example of

10830-403: The taxon is termed a synonym ; some authors also include unavailable names in lists of synonyms as well as available names, such as misspellings, names previously published without fulfilling all of the requirements of the relevant nomenclatural code, and rejected or suppressed names. A particular genus name may have zero to many synonyms, the latter case generally if the genus has been known for

10944-425: The teeth in Mylodon probably resulted in a rather low processing capacity for the food in the mouth. This can result in either a high rate of fermentation in the gastrointestinal tract and/or a very slow metabolism concluded. The latter is the case with today's sloths. This is due to the long passage time of the food of up to a week through the large, multi-chambered stomach. It can be assumed that this also applies to

11058-406: The thickness about 7.5 cm. The joint ends, on the other hand, were markedly wider, around 30 cm at the knee end and around 26 cm at the foot end. The thighbone reached the shin with only about half of its length, a characteristic of mylodonts. This bone, too, was clearly flat with a thickness that was only half the value of the width at the shaft. The fibula is so far only fragmented. It

11172-430: The three inner digits were probably clawed, but only of the second digit have all bone elements been documented. The metacarpal bone was 7.8 cm long and was built very gracefully. The first phalanx was extremely short and only about 2.5 cm long, the second was about 4.2 cm long and the third at least 11.5 cm. It was tubular and went forward into an extension on which the claw rested. The first phalanges of

11286-512: The two outer digits were significantly reduced in length. Only individual root bones of the foot, such as the talus, are present. Mylodon is one of the few extinct mammals that has mummified skin remains. The most important location for such finds is the Cueva del Milodón in the Chilean province of Última Esperanza, where the first skin parts were brought to light at the end of the 19th century. Individual pieces have lengths of up to 150 cm, but have shrunk through drying processes. Its thickness

11400-566: The values quoted are the mean of "accepted" names alone (all "uncertain" names treated as unaccepted) and "accepted + uncertain" names (all "uncertain" names treated as accepted), with the associated range of uncertainty indicating these two extremes. Within Animalia, the largest phylum is Arthropoda , with 151,697 ± 33,160 accepted genus names, of which 114,387 ± 27,654 are insects (class Insecta). Within Plantae, Tracheophyta (vascular plants) make up

11514-429: The virus species " Salmonid herpesvirus 1 ", " Salmonid herpesvirus 2 " and " Salmonid herpesvirus 3 " are all within the genus Salmonivirus ; however, the genus to which the species with the formal names " Everglades virus " and " Ross River virus " are assigned is Alphavirus . As with scientific names at other ranks, in all groups other than viruses, names of genera may be cited with their authorities, typically in

11628-523: The wind. A 2021 study on stable isotope ratios concluded that Mylodon must have been at least sporadically omnivorous. In general, large mylodonts are ground-dwelling animals. The lower section of the hind leg, which is very short compared to the upper, is also found in Mylodon , whose tibia is 27 cm in length and only half as long as the thigh bone, 59 cm in length. In comparison, the Megatheriidae possess significantly longer lower leg portions, about

11742-428: The wrist, the pea bone was clearly flat, its shape resembled that of Glossotherium , but differed from the corresponding bone of other Mylodonts with spherical, walnut-like or a pyramidal shape. The fourth digit had formed the longest metacarpal bone, while that of the fifth was only slightly shorter. The respective bones measured there around 12.5 and 10.7 cm in length. As with Glossotherium and Paramylodon , only

11856-461: The year before in the flood plains of the Río de la Plata north of Buenos Aires . The largely intact skull was characterized by a short and broad snout and by a dentition consisting of a total of 18 teeth, of which the foremost tooth in each case showed a canine design. Based on the similarities in dental structure with the flat, molar-like teeth, Owen placed the skeleton in the genus Mylodon and introduced

11970-501: Was a primarily a grazer , feeding on grasses and sedges . Mylodon has generally only a single recognised species, Mylodon darwini , which was described by Richard Owen in 1840 based on remains collected in the Pampas by Charles Darwin (for whom the species is named) during the Voyage of the Beagle . Some recent authors suggest that there were two species, with M. darwini restricted to

12084-480: Was built gracefully. Their length was around 37 cm. The olecranon, i.e. the upper articular process, took up about 8.1 cm of it, which corresponds to about 22% of the total length and is significantly less than in comparison with Glossotherium and Lestodon . It was laterally narrowed, which is also found in Paramylodon . The spoke largely resembled that of Glossotherium and was compact and straight built with

12198-414: Was drawn in on the shaft and widened at the joint ends, with the upper joint end showing more pronounced curves than in Glossotherium . The hand comprised a total of five digits (I to V), whereby the metacarpal bone was fused with the large polygonal bone on the first digit. This created the so-called Metacrapal Carpal Complex (MCC for short), which is typical for many ground sloths. As a special feature of

12312-416: Was elongated, more noticeable than in Glossotherium and Lestodon , since in Mylodon the area in front of the teeth, in particular, is strongly elongated. The horizontal bone body increased continuously in height towards the rear, below the last molar it was about 10.5 to 12.7 cm. The symphysis at the front end for the jointing of the two halves of the lower jaw was about 12.4 cm long. Here the lower edge of

12426-473: Was mainly distributed in the southern part of South America. Fossil finds are known from Argentina, Chile, southern Bolivia, Uruguay, Paraguay and southern Brazil. Thus, the colonized regions include very far southern sites on the island of Tierra del Fuego as well as most of Patagonia northward to the Pampas region. Its northern limit was around 19.6° S, while its southern limit reached the range at about 53° south. The Tres Arroyos site on Tierra del Fuego and

12540-498: Was more well-adapted to a mixed-vegetation diet, which was picked up with the help of a movable upper lip. The loss of the front teeth in the upper row of teeth also leads to the assumption that, comparable to cattle, there was a horn-like structure on the middle jawbone that could be used to pluck the food. The entire anterior cranial structure of Mylodon is relatively solid, combined with a partially ossified nasal septum, it can be assumed that relatively high chewing forces acted when

12654-543: Was over 10 cm, stood out due to its hemispherical, but laterally somewhat flattened shape. A distinct deltopectoral ridge ran down the shaft, which acted as an anchor point for the shoulder muscles. As with many ground sloths, the lower end of the joint extended far and brought it here to a width of almost 26 cm. In part, this was caused by a massive internal epicondyle. The articular surfaces (capitulum and trochlea) were almost perpendicular to each other and did not form such an obtuse angle as in Glossotherium . The cubit

12768-411: Was significantly smaller than the giant Lestodon . In terms of physique, it largely corresponded with the other large ground-living sloths. Especially in the construction of the skull, Mylodon differed significantly from other related forms. Its length varied between 59 and 71.5 cm, which is significantly longer than Glossotherium or Lestodon . At the skull it was between 16.5 and 22.5 cm wide, in

12882-420: Was slim, the anterior attachment began above the third and fourth molars. It did not form a solid end with the rear arch attachment. As is usual with sloths, the front arch base consisted of three appendages: one ascending, one horizontal, and one descending, the former of which was the longest. The rear arch formed a triangular plate. The occiput bent at an angle of 120° from the roof of the skull. The underside of

12996-500: Was that the upper canine-like tooth of each row was completely regressed and only the molar-like four rear teeth were found here. In the lower row of teeth, the anterior caniniform tooth was transformed into a molariform. The dentition thus consisted of a total of 16 teeth. This is somewhat reminiscent of Paramylodon , in which the upper canine-shaped teeth were also missing, but the lower ones had retained their strikingly pointed shape. In contrast to this, Glossotherium and Lestodon had

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