DISCOVERY OF THE TITANOTHERES AND ORIGINAL DESCRIPTIONS 



199 



These start from the prominent cingular protostyle and cul- 

 minate in a more elevated portion some 13 millimeters to the 

 rear, diminishing again behind this point. 



Attention may also be called to the presence in one of the 

 specimens of a broad, gently rounded median fold iu the 

 center of the external paraconal wall of the tooth, although in 

 the other specimen no such fold is visible. According to 

 Earle such a median rib is characteristic of all the early titano- 

 theres, tending to vanish in the upper Eocene and being 

 entirely absent in the Oligocene subfamily of the Titano- 



Measurements of inferior teeth Pi-m^ and superior teeth m'-m^ 



Millimeters 

 P2-m3: Huerfano A. L. priscum (ref.), Am. Mus. 17526. 67 

 Wind River B. L. popoagicum (type), Am. Mus. 



4863 69 



Wind River B. L. progressum (type), Am. Mus. 



14917 (estimated) 71 



Huerfano A. L. magnum (type), Am. Mus. 17527. 74 

 Mi-m^: Huerfano A. L. priscum (ref.), Am. Mus. 17529. 21. 5 

 Huerfano A. L. priscum (ref.). Am. Mus. 2688.. 22. 5 

 Wind River B. L. popoagicum (ref.), Am. 



Mus. 14902 25 



Huerfano A. L. progressum (ref.), Am. 



Mus. 17530 23.5 



Wind River B. L. magnum (ref.). Am. 



Mus. 15600 27.5 



These measurements show that there is not a 

 great range in size between the smaller and the 

 larger animals referred to this genus. 



Etymology. — magnum, large. 



Present determination. — A valid specific 



Figure 154. — Type (holotype) of Lambdotherium magni 

 Lower jaw. Am. Mus. 17527. After Osborn, 1919. Natural size. 



theriinae. In any case the external lobes are broad and flat 

 and considerably elevated, hli;e those of the latest members of 

 the Palaeosyops-Diplacodon phyla. 



Perhaps taking everything into consideration the present 

 species shows greater affinities with Telmatherium than any 

 other known titanotherid genus. 



Etymology.- — Mrmanicum, relating to Burma. 



Present determination. — Position uncertain. The 

 very close beading and massive cones of the single 

 grinding tooth figured suggest comparison with 

 Palaeosyops, a progressive species like P. copei. 

 These teeth might belong to a chalicothere, such as 

 Macrotherium or Moropus, but the resemblance is 

 not close. 



Lambdotherium magnum Osborn, 1919 



Cf. Lambdotherium magnum, this monograph, page 288 



Original reference. — Am. Mus. Nat. Hist. Bull., vol. 

 41, p. 562, fig. 3, 1919 (Osborn, 1919.494). 



Type locality and geologic Jiorizon. — Lower horizon of 

 the Huerfano formation (Huerfano A) of Colorado. 



Specific characters. — Osborn writes: 



Exceeding in size any other known lambdothere is the type 

 jaw (Am. Mus. 17527) from the Garcia Canon, lower Huerfano, 

 containing a complete inferior series, p2-m3 of both sides, 

 represented in Figure 3. (1) These teeth exceed in length over 

 all (74 mm.) those of the type of L. popoagicum, in which the 

 same teeth measure 69 millimeters. (2) P3 has a rudimentary 

 metaconid and paraconid, in the same stage of evolution as in L. 

 popoagicum. (3) Of similar large size is a referred specimen. 

 Am. Mus. 15600, from the Big Horn, west end of Tatman Moun- 

 tain. "These_ referred grinders, m', m^, coincide closely in size 

 with the type of L. magnum and may be regarded as a paratype. 

 [See fig. 154.] 



stage. 



Eotitanops minimus Osborn, 1919 



Cf. Eotitanops minimus, this monograph, page 296 



Original reference. — Am. Mus. Nat. Hist. Bull., vol. 

 41, p. 564, fig. 4, A, A\ 1919 (Osborn 1919.494). 



Type locality and geologic Jiorizon. — Two miles north 

 of Gardner, Huerfano Basin, Colorado; from the lower 

 level of the upper horizon of the Huerfano formation 

 (Huerfano B). 



Specific characters. — Osborn writes: 



In reference to the fact that it is the smallest true titanothere 

 known, these type lower molar teeth, pi-ms. Am. Mus. 17439 

 (fig. 4, A, A'), * * * are assigned a new specific name 

 on the following grounds: (1) The measurement of p4-m3 (53 

 mm.) is much less than that (58) of the corresponding teeth 



E.minlmus, Type 



Figure 155. — Type (holotype) of Eotitanops minimus 



Lower teeth. Am. Mus. 17439. After Osborn, 1919. A, Lingual or internal view; 

 A^, crown view. Natural size. 



in E. gregoryi; (2) the other characters are so similar to those 

 of E. gregoryi as to suggest that this is a related form. [See 

 fig. 155.] 



The accompanying figures (fig. 4, A, B, C) exhibit the 

 dimensional proportions of the above species of Eoiilaiiops. 

 It has been found from the large number of measurements of 

 Eocene titanotheres that no single species exhibits so great 

 a range of size. 



Etymology. — minimus, small. 



Present determination. — ^A valid specific stage. 



