Huaridelphis raimondii, a new early Miocene Squalodelphinidae (Cetacea, Odontoceti) from the Chilcatay Formation, Peru

Figures & data

FIGURE 1. Map of the Pisco-Ica desert, southern coast of Peru, showing the two localities of the Chilcatay Formation where squalodelphinids, including Huaridelphis raimondii, n. gen. et sp., were found: Ullujaya and Zamaca. Marine vertebrate-rich localities of the Mio-Pliocene Pisco Formation are also indicated: Cerro Colorado, Cerro los Quesos, and Cerro la Bruja.

FIGURE 2. Map of the Chilcatay Formation locality Ullujaya, where the holotype of Huaridelphis raimondii, n. gen. et sp., was found together with other cetacean remains, marine turtles, and fishes. Cerro Buque, from where a section of the Chilcatay Formation was published (Alván De la Cruz, 2008), is a short distance northwest to Ullujaya. Curved lines represent limits of more consolidated beds visible from aerial views.

FIGURE 3. Huaridelphis raimondii, n. gen. et sp., MUSM 1396 (holotype), skull in dorsal (A, B, C; detail of the vertex) and left lateral (D) views. Diagonal solid lines indicate major breaks. Scale bar for A, B, D equals 10 cm. Scale bar for C equals 2 cm.

FIGURE 4. Huaridelphis raimondii, n. gen. et sp., MUSM 1396 (holotype), skull in ventral (A, B), posterior (C), anterior (D), and right lateral (E, F) views. Diagonal solid lines indicate major breaks.

FIGURE 5. Huaridelphis raimondii, n. gen. et sp., MUSM 1403, skull in dorsal (A, B; detail of the vertex) and left lateral (C) views; symphyseal portion of mandible in left lateral (D) and dorsal (E) views; mandibular tooth in lateral view (F); incomplete atlas in anterior (G) and ventral (H) views; axis in anterior (I), ventral (J), posterior (K), and right lateral (L) views; four cervical vertebrae in anterior views (M–P); four thoracic vertebrae in posterior (Q, W), anterior (S, T, V), and right lateral (R, U, X) views; almost complete right rib in anterior (ZC) and posterior (ZD) views; proximal fragment of left rib in anterior view (ZE). Huaridelphis raimondii n. gen. et sp., MUSM 599, caudal vertebra in anterior (Y) and left lateral (Z) views; posterior tooth in lateral (ZA) and lingual (ZB) views. Diagonal solid lines indicate major breaks. Scale bar for A, C, D, and E equals 10 cm. Scale bars for F, ZA, and ZB equal 1 cm. Scale bar for G–Z and ZC–ZE equals 5 cm.

FIGURE 6. Huaridelphis raimondii, n. gen. et sp., MUSM 1396 (holotype), incomplete right periotic in dorsal (A, B), ventral (C, D), and lateral (E, F) views. Huaridelphis raimondii, n. gen. et sp., MUSM 599, left periotic in dorsal (G, H), dorsolateral (I, J), ventral (K, L), medial (M, N), and lateral (O, P) views. Diagonal solid lines indicate major breaks.

FIGURE 7. Squalodelphinidae aff. Huaridelphis raimondii, MUSM 603, incomplete skull in dorsal (A) and left lateral (B) views; left periotic articulated to the skull in ventral view (C); left malleus in posterior (D, E), and medial (F, G) views; left incus in medial (H, K), lateral (I, L), and dorsal (J, M) views; left tympanic bulla in medial (N, R), ventral (O, S), dorsal (P, T), and lateral (Q, U) views. Diagonal solid lines indicate major breaks. Scale bar for A and B equals 10 cm. Scale bars for C and N–U equal 2 cm. Scale bar for D–M equals 1 cm.

FIGURE 8. Consensus tree (A) and 50% majority consensus tree (B) of 60 equally parsimonious cladograms showing the relationships of Huaridelphis raimondii, n. gen. et sp., with the other Platanistoidea having lost double-rooted teeth. Tree length = 55, consistency index = 0.76, and retention index = 0.90. Numbers associated with the nodes in B are bootstrap values. See text for discussion and Appendices 1 and 2 for description of characters and data matrix.

TABLE 1. Measurements (in mm) on the skulls of Huaridelphis raimondii, n. gen. et sp., compared with two skulls of Notocetus vanbenedeni (measurements partly taken from True, 1910).

	Huaridelphis raimondii, n. gen. et sp.		Notocetus vanbenedeni
Dimension	Holotype, MUSM 1396	MUSM1403	MUSM 599	Holotype MLP 5-5	AMNH 9485
Measurements of True (1910)
Condylobasal length	494	+486	—	582	634
Rostrum length	330	317	—	368	433
Maximum width between temporal crests	128	e109	117	140	142
Distance between upper margin of foramen magnum and nuchal crest	69	—	—	91	97
Height of foramen magnum	31	—	29	33	40
Width of foramen magnum	35	—	31	33	40
Height of occipital condyle	37	—	38	47	46
Length of temporal fossa	81	e63	—	102	115
Height of temporal fossa	59	58	—	71	74
Minimum width between temporal crests	109	e90	e102	135	128
Width between orbit centers	173	165	—	230	252
Anterior width of nasals	28	26	e32	46	48
Width at rostrum base	92	90	—	114	142
Width of premaxillae at rostrum base	55	54	e56	—	89
Maximum distance between premaxillae anterior to bony nares	9	7	—	e22	28
Width of maxillae at mid-length of rostrum	30	28	—	44	52
Width of premaxillae at mid-length of rostrum	16	14	—	28	30
Length of posterior alveolus	4.5	5.0	5.6	—	9
Width of posterior alveolus	3.7	e5.0	4.7	—	6.5
Length of alveolus at mid-length of rostrum	5.0	4.1	—	7	9.5
Width of alveolus at mid-length of rostrum	4.5	4.1	—	5.5	8
Length of anterior alveolus	—	5.5	—	11	11.5
Width of anterior alveolus	—	4.2	—	6	9
Length of tooth row	275	268	—	315	363
Additional measurements
Number of teeth per upper tooth row	+28/28	29/29–30	—	22–23	21–22
Height of rostrum at mid-length	24	24.5	—	—	—
Cranium length from antorbital notches to occipital condyle	177	+148	—	—	—
Postorbital width of skull	183	173	—	—	—
Bizygomatic width of skull	207	e200	—	—	—
Maximum width of premaxillae on cranium	73	79	—	—	—
Width of right premaxillary sac fossa	27	28	—	—	—
Width of left premaxillary sac fossa	28	27	—	—	—
Width of bony nares	33	31	e34	—	—
Maximum length of nasal	15	15	—	—	—
Length of medial suture between nasals	10	15	—	—	—
Minimum distance between maxillae across vertex	40	39	44	—	—
Length of medial suture between frontals on vertex	19	19	—	—	—
Orbit length	55	52	58	—	—
Squamosal length from ventral tip of postglenoid process to anterior tip of zygomatic process	—	—	88	—	—
Width of occipital condyles	78	—	74	—	—

+, incomplete; —, missing data; e, estimate.

TABLE 2. Measurements (in mm) of vertebrae of Huaridelphis raimondii, n. gen. et sp., MUSM 1403 (cervicals and thoracics) and MUSM 599 (caudal).

Element	Centrum length	Maximum centrum height	Width of anterior epiphysis	Width of posterior epiphysis	Width of neural canal	Height of neural canal	Maximum width
MUSM 1403
Axis	—	29.5	—	39	29	—	87
Cervical C	18	32	—	36.5	—	—	e80
Cervical D	+22.5	33	—	37	—	—	—
Cervical E	+20	+36	—	36	—	—	—
Cervical F	+17	35.5	—	33.5	—	—	—
Thoracic A	27.5	31	34	36	32.5	32.5	98
Thoracic B	+32	30.5	36	—	27	31.5	79
Thoracic C	36	+29	—	—	—	30	—
Thoracic D	+34	30	e36	e44	23.5	27	e69
MUSM 599
Caudal	36	44	42	36.5	—	—	—

The vertebrae of MUSM 1403 are listed in an anteroposterior sequence reflecting the relative position of each vertebra, but intermediary vertebrae are missing (one cervical and an unknown number of thoracics). +, incomplete; —, missing data; e, estimate.

TABLE 3. Comparison of rostral measurements (width of rostrum and premaxillae at different levels, in mm) in the squalodelphinids Huaridelphis raimondii, n. gen. et sp., MUSM 1396 and aff. Huaridelphis raimondii MUSM 603.

	Huaridelphis raimondii MUSM 1396		aff. Huaridelphis raimondii MUSM 603
Dimension	Rostrum	Premaxillae	Rostrum	Premaxillae
Width at antobital notches	92	55	91	62
Width anterior to notches
30 mm	78	51	—	50
60 mm	61	38	—	40
90 mm	44	26	65	34
120 mm	33	20	55	28
150 mm	31	16	48	26
180 mm	27	15	41	23
210 mm	23	13	—	—
240 mm	20	13	—	—
270 mm	19	—	—	—
300 mm	19	—	—	—

—, missing data.

Table

	5	10	15	20	25	30	35	37
Huaridelphis	00011	01100	11110	11111	12100	0???0	?1011	??
MUSM 603	? ?011	01100	1??10	?1111	1??0?	01020	01???	??
Notocetus	00011	01100	11110	11111	12100	01100	11001	11
Squalodelphis	00012	11100	1?110	?1101	12100	01100	1100?	??
Medocinia	??012	11101	1?110	1110?	?????	?????	?1???	??
USNM 475596	??0??	?1101	11110	?110?	?????	?????	?10??	??
Phocageneus	? ????	?????	?????	????1	12100	01100	110?1	??
Platanista	00111	00110	11110	21102	01001	11010	01110	11
MUSM 1611	?????	?????	?????	????2	01001	1????	?????	??
Zarhachis	10111	00111	11110	11102	00010	01010	01110	??
Pomatodelphis	10111	00111	11110	11102	00010	01010	01110	??
Zarhinocetus	10100	10100	10?10	0100?	00000	0???0	?1?1?	??
Allodelphis	10100	10000	10?10	1100?	?????	?????	?1?1?	??
Eurhinodelphis	11101	00000	10001	00000	00000	00011	01?10	??
Xiphiacetus	11101	001a0	10000	000a0	00000	00011	?1010	00
Ziphiodelphis	11101	00100	10001	00000	00000	00011	01010	??
Waipatia	00001	00000	00000	00000	00000	00000	00000	??
Squalodon	10000	00000	00000	00000	00000	00000	00000	??
Zygorhiza	00000	00000	00000	00000	00000	00000	00000	00

True, F. W. 1910. Description of a skull and some vertebrae of the fossil cetacean Diochotichus vanbenedeni from Santa Cruz, Patagonia. Bulletin of the American Museum of Natural History 28:19–32.

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