JOURNALOF PALEONTOLOGY,V. 61, NO. 2, P. 388-423, 16 FIGS.,MARCH 1987 MIOCENE RHINOCEROSES FROM THE TEXAS GULF COASTAL PLAIN DONALD R. PROTHEROAND EARL M. MANNING Departmentof Geology, OccidentalCollege, Los Angeles, California90041 and Museum of Geoscience, LouisianaState University, Baton Rouge 70803 ABSTRACT--Fourspecies of rhinocerosoccur togetherin the Barstovian(middle Miocene) faunas of southeast Texas, a unique situation in the Miocene of North America. Two are assigned to normal contemporaryHigh Plains species of Aphelopsand Teleoceras,and two to dwarf species of Peracerasand Teleoceras.The dwarfPeraceras is a new species, P. hessei.The dwarfTeleoceras is assignedto Leidy's (1865) species "Rhinoceros"meridianus, previously referredto Aphelops. "Aphelops"profectus is here reassignedto Peraceras. The late Arikareean(early Miocene) Derrick Farm rhino, erroneouslyreferred to "Caenopus premitis"by Wood and Wood (1937), is herereferred to Menocerasarikarense. Menoceras barbouri is reportedfrom the early Hemingfordian(early Miocene) Garvin Gully local fauna of southeast Texas. The rhinos from the early ClarendonianLapara Creek Fauna are tentativelyreferred to Teleocerascf. major. The three common genera of middle late Miocene rhinocerosesof North America (Aphelops, Peraceras, Teleoceras)are rediagnosed.Aphelops and Peracerasare more closely related to the EurasianAceratherium and Chilotherium(all four togetherforming the Aceratheriinae)than they are to the American Teleoceras.Contrary to Heissig (1973), Teleocerasis more closely relatedto the living rhinocerosesand their kin (togetherforming the Rhinocerotini)than it is to the Acer- atheriinae. INTRODUCTION of Leidy's species. Most authors since Mat- AMONGthe first mammalian fossils described thew (e.g., Hesse, 1943; Quinn, 1955; Patton, from Texas was a fragmentary upper molar 1969) have referredthe largerrhinoceros ma- of a rhinoceros from the Texas Gulf Coastal terial from the middle Miocene of Texas to Plain. The specimen was given to J. Leidy by "Aphelops"meridianus, if generic-leveliden- B. F. Shumard of St. Louis, Missouri. Leidy tification was attempted at all. (1865) described this tooth, illustrated it Hesse (1943) was the first author to rec- (1869, P1. 23, fig. 10; see Figure 10.1-10.3), ognize a smallerrhinoceros in the Texas Gulf and gave it the name Rhinocerosmeridianus. Coast Barstovian faunas. He described and The only locality informationgiven by Leidy named a new species, Aphelops rileyi, in a was that "it was derived from a tertiary [sic] manuscriptthat was incomplete at his death deposit in Washington county [sic], Texas, in 1944, and never published. This smaller and presents much the general aspect of the rhinoceros material was referredto Dicera- Mauvaises Terres fossils of the White River, theriumby Quinn (1955) and Patton (1969), Dakota, with which it is probably cotempo- apparently due to identifications made by H. rary [sic] in age" (1869, p. 229). E. Wood (J. A. Wilson, personal commun.). In 1875 and 1877, Cope referred some Quinn (1955, p. 75) mentioned a small rhi- specimens from the Santa Fe Group of New noceros "no larger than Diceratherium, but Mexico to the species meridianus,but placed with characters of Teleoceras including the this species in his new genus Aphelops.Mat- reduced number of cheek teeth," suggesting thew (1932) pointed out that Cope's "meri- "a primitive but direct ancestor to the upper dianus" did not correspond well to Leidy's Miocene and Pliocene species." Quinn gave type specimen,and was not from Texas. Mat- no catalogue number for this specimen. Based thew considered the name meridianusinde- on this brief and nondiagnostic description, terminate until adequate topotypes were it is unlikely that he actually recognized the known. Matthew (1932, fig. 2) also figureda dwarf Teleoceras, since there is no complete specimen (UCMP 31043) from near the type skull of it in the Texas Memorial Museum locality that he believed to be representative collections. All of the "Diceratherium"-sized Copyright @ 1987, The Paleontological Society 388 0022-3360/87/0061-0388$03.00 MIOCENE RHINOCEROS FROM TEXAS 389 skulls (probably in reference to Menoceras of Natural History, New York, N.Y.; F:AM, arikarense,the Agate Springrhino) in the lat- Frick Collection, American Museum of Nat- ter collection are of the dwarf Peraceras.Al- uralHistory, New York, N.Y.; l.f., local fauna though many (but not all) advanced Teleoc- (sensu Tedford, 1970); MCZ, Museum of eras reduce the premolarsand lose P2/2, this Comparative Zoology, Harvard University, is not a diagnosticfeature of the genus. Thus, Cambridge, Mass.; N, sample size; PU, "reduced number of cheek teeth" is not Princeton University Museum, Princeton, diagnostic of Teleoceras.In short, the pub- N.J.; OR, observed range;s, standarddevia- lished literature is in great confusion con- tion; TAM, Texas A&M University, College cerning Texas Gulf Coast Miocene rhinoc- Station, Tex.; TMM, Texas Memorial Mu- eroses. seum, University of Texas at Austin;UCMP, In 1936, the FrickLaboratory of the Amer- University of CaliforniaMuseum of Paleon- ican Museum of Natural History began col- tology, Berkeley, Calif.; UNSM, University lecting in the Texas Gulf Coastal Plain. The of Nebraska State Museum, Lincoln, Nebr.; excavations were supervisedchiefly by N. Z. USNM, United States National Museum, Ward,and continued until 1964. Most of the Washington,D.C.; ., mean. large collection from this area remains un- For ease of word processing,the system of described. Descriptions of some of the ro- dental abbreviations of Jepsen (1966) is dents(Wahlert, 1976), horses (MacFadden and adopted here. Thus, upper premolars and Skinner, 1977, 1981; Skinner and MacFad- molars are indicated by upper case "P" or den, 1977), protoceratidartiodactyls (Frick, "M", lower premolars and molars by lower 1937; Patton and Taylor, 1971, 1973), lep- case "p" or "m". tomerycids (Taylor and Webb, 1976), and A note on endings:the -cerassuffix in rhino oreodonts (Schultz and Falkenbach, 1941) genera (such as Peraceras or Teleoceras) is have been published. While curatingthe rhi- neuter in gender;the suffix -ceros (as in Rhi- noceros material in the Frick Collection, the noceros)is masculine.Since adjectivalspecies junior authorfound that the BarstovianTex- names must agree with the genus in gender as Gulf Coastal Plain faunas contained four (International Code of Zoological Nomen- sympatricspecies of rhinoceros.Two of these clature, Article 11, section g), a number of appeared to be similar to the High Plains traditionally-accepted species names have Aphelops megalodus and Teleoceras medi- been corrected.Thus, Peraceras has species cornutum,but there was also a dwarf Teleoc- superciliosumand profectum;Teleoceras has eras and a dwarf aceratherine rhinoceros species medicornutum,proterum, and meri- present. The latter was first identified as a dianum. Similarly, Brachypotheriumameri- dwarfAphelops(Prothero and Sereno, 1980), canus Yatkola and Tanner, 1979, is here but comparisonwith more complete material amended to B. americanum, since the suffix in the Texas Memorial Museum collection -theriumis also neuter. has shown that the dwarf aceratherineis ac- tually a dwarf Peraceras. The occurrenceof four differentrhinoceroses in the Texas Bar- LOCALITIES AND STRATIGRAPHY stovian faunas probably caused some of the The Miocene of the Texas Gulf Coastal taxonomic confusion outlined above. Plain has been collected by a number of in- The interestingmorphological and ecolog- stitutions over the years, but the major col- ical implications of this occurrenceare dis- lections of fossil vertebratesare at the Texas cussedelsewhere (Prothero and Sereno, 1982). MemorialMuseum of the University of Tex- In this paper,the systematics of the Miocene as at Austin, the Texas A&M University rhinoceroses of Texas are reviewed, and an (presently on loan to the Texas Memorial attempt to clear up some of the confusion Museum), and the Frick Collection of the regarding the early, primitive members of the American Museum of Natural History. Each genera Aphelops, Teleoceras, and Peraceras institution has a distinct set of localities, list- is made. ed in Table 1 and shown in Figure 1. The Abbreviations. -AMNH, Department of detailed locality information is given in Hesse Vertebrate Paleontology, American Museum (1943) and Patton and Taylor (1971, table 2). 390 DONALDR. PROTHEROAND EARL M. MANNING TABLE 1-Areal distributionof fossil localities (see Figure 1). Num- ber County Fauna Locality 1 Tyler Burkeville West of Doucette, near Woodville 1 Tyler Cold Spring TMM 40662, Belts Creek 2 Tyler Cold Spring TMM 30009, 31087, 8 mi southwestof Woodville 3 Polk Burkeville TMM 30157, Moscow l.f. 4 Polk Cold Spring Near Swartaut 5 Tyler Cold Spring TMM 40623, Push Creek 6 San Jacinto Cold Spring TMM 31219, Cold Springl.f. (=F:AM Donohoe Farm) 6 San Jacinto Cold Spring McMurrayPits 1 and 2 6 San Jacinto Burkeville Trinity River Pit 1 (=TMM 40196) 6 San Jacinto Burkeville StephenCreek 7 San Jacinto Cold Spring TMM 31191, San Houston l.f. 8 San Jacinto Burkeville TMM 31243, Point Blankl.f. 9 San Jacinto Burkeville TMM 31190, Point Blank l.f. 10 San Jacinto Burkeville TMM 31242, Point Blank l.f. 11 Walker Garvin Gully TMM 30873, Aiken Hill l.f. 12 Grimes Burkeville TMM 40290, near Navasota 13 Washington ?Burkeville Leidy'dlocality, fide Hesse, 1943 14 Washington Cold Spring TMM 31272, southeastof ChapellHill 15 Washington Garvin Gully TMM 40106, Farm Road 244 15 Washington Garvin Gully