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 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 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 the type species.Johannes Theodor Reinhardt: Beskrivelse af Hovedskallen af et Kæmpedovendyr, Grypotherium darwini. In: Det Kongelige Danske Videnskabernes Selskabs Skrifter. 5 Række. Naturvidenskabelig og Mathematisk Afdeling 12 (5), 1879, pp. 351–381 ( archive.org ). 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 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.Florentino Ameghino: Contribución al conocimiento de los mamíferos fósiles de la República Argentina. In: Actas de la Academia Nacional de Ciencias. Volume 6, 1889, pp. 1-1027 (pp. 734-744). 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 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.
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 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 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 the TYpE sPecies.JOHanNes tHeodor rEinhaRDt: beSkrIvElsE AF hoveDskallen af et kæmpeDOvendyr, gRyPoTherIuM .dARwiNI. iN: dEt kongEliGe DanSKe viDensKABERNeS Selskabs skrIfTeR. 5 række. natURvIdenSkABeLig og mAThematIsk aFdElING 12 (5), 1879, Pp. 351–381 ( archiVE.ORg ). 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 AGReEin.g 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 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.floRENtINo amegHiNo: cOnTrIbucióN aL conOciMieNto de lOs MaMífERos FÓSIlES De la rEPúblICA argeNtina. iN: aCtAs De La AcaDemIa NaciONal De cIencias. volUmE 6, 1889, pp. 1-1027 (PP. 734-744). 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 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.