Pisco Formation

The Pisco Formation of the Pisco Basin consists of tuffaceous sandstones, diatomaceous yellow to gray siltstones and a basal conglomerate.^[7] The formation is deposited from Pisco in the north to Yauca in the south. The northern portion is known as the Ocucaje Area and the southern part as the Sacaco Area.^[8] The total thickness of the formation is estimated at 640 metres (2,100 ft).^[9] The formation unconformably overlies the Chilcatay and Caballas Formations.

The Pisco Formation has provided a rich resource of marine fauna, including marine mammals like cetaceans and seals, large fishes, reptiles, and penguins.^[10] It is also one of the richest sites in the world for fossil cetaceans, with close to 500 examples being found in the formation.^[11]

The oldest fossils of the aquatic sloth Thalassocnus (T. antiquus) come from the Aguada de Lomas horizon of the Pisco Formation and were dated at roughly 7 Ma. The youngest specimen (T. carolomartini) was found in the Sacaco horizon and dated to approximately 3 Ma.^[12] Thalassocnus was preyed upon by the probable apex predators of the environment, Livyatan and megalodon.^[13][14] The youngest strata belonging to the formation have been dated at 2 Ma, corresponding to the Early Pleistocene (Uquian). Fossils of the modern Humboldt penguin were found in these deposits at the Yauca locality.^[15]

Taxa	Species	Description	Images	Notes
Diplochaetetes	D. mexicanus	A cirratulid bristle worm		[17]

Taxa	Species	Description	Images	Notes
Myliobatis	indet. sp.	A species of eagle ray		[10]

Taxa	Species	Locality	Materials	Description	Images	Notes
Carcharias	C. taurus			Archaic sand tiger shark		[16]
Carcharhinus	indet. sp.			A requiem shark		[10]
Carcharodon	C. carcharias			Archaic great white shark and close relative, respectively		[20][16]
	C. hubbelli		Jaw, multiple teeth, and 45 vertebral centra
	C. hastalis		Fossilized jaws.	The broad-toothed "mako"		[10]
	C. plicatilis
Hexanchus	H. gigas			A cow shark		[20]
Isurus	I. oxyrhinchus			Archaic shortfin mako		[21]
Otodus	O. megalodon	Sub-Sacaco, Cerro Colorado, Aguada de Lomas, and El Jahuay	Multiple teeth, vertebrae, and dentition	The largest of the megatoothed sharks (Otodontidae) and of all fishes		[10]

Taxa	Species	Locality	Materials	Description	Images	Notes
Ciconiidae indet.	Gen. et sp. indet.			A stork		[26]
Fulmarus	Indet. sp.			A petrel		[16]
Morus	M. peruvianus	Sud-Sacaco	A set of limb elements	A relative of living gannets (Sulidae)		[22]
Perugyps	P. diazi	Sud-Sacaco	A limb element (right carpometacarpus).	A New World vulture (Cathartidae)		[22]
Pelagornis	Pelagornis sp.	Aguada de Lomas	Proximal carpometacarpus and right humerus ends	A pseudotoothed bird (Pelagornithidae)		[21][27]
Pelecanus	Indet. sp.			A pelican		[28]
Phalacrocorax	P. aff. bougainvillii			A relative of the Guanay cormorant		[16][29]
	cf. Phalacrocorax sp.			Probable cormorant remains
Rhamphastosula	R. aguierrei	Sud-Sacaco West	A cranium skull	A sulid bird with an enlarged beak		[16][30]
	R. ramirezi	Sud-Sacaco West	A skull
Spheniscus	S. humbodti	Sud Sacaco		Archaic Humboldt penguin		[15]
	S. megarhampus	Sud Sacaco	A partial skeleton	Large-beaked banded penguin		[15]
	S. muizoni	Cerro la Bruja	A partial skeleton.	The oldest banded penguin		[31][32]
	S. urbinai	Sud-Sacaco West	A partial skeleton (partial skeleton with skull)	A larger banded penguin than S. muizoni		[15]
Sula	S. brandi	Cerro Colorado	A neurocranium lacking interorbital septum, lacrimals, palatines, pterygoids, jugals, quadrates, and right quadratojugal.Proximal portion of the beak, including most of the right dentary and angular.	Relatives of living boobies (Sulidae)		[22][33]
	S. magna	Sud Sacaco	A set of limb elements.
	S. sulita	Sud Sacaco	A limb element (coracoid)

Taxa	Species	Locality	Material	Description	Images	Notes
Acrophyseter	A. deinodon	Sud-Sacaco	A skull	A small raptorial physeteroid (sperm whale relative)		[22][34]
	A. robustus	Cerro la Bruja	A skull
Atocetus	A. iquensis	Cero la Bruja	A skull	A small kentriodontid whale		[35][36]
Australithax	A. intermedia	El Jahuay		A long-snouted porpoise (Phocoenidae)		[37]
Balaenoptera	B. siberi	Aguada de Lomas	A partial skeleton	Archaic rorqual (Balaenopteridae)		[21][38]
Belonodelphis	B. peruanus	Cerro la Bruja	A skull	An elongated oceanic dolphin (Delphinidae)		[21][35][39]
Brachydelphis	B. jahuayensis	El Jahuay	A partial skull	An early oceanic dolphin (Delphinidae)		[21][35][40][41]
	B. mazeasi	El Jahuay	A partial skull
Brujadelphis	B. ankylorostris	Cerro la Bruja	A skull with complete jaw	A toothed whale of uncertain relation (incertae sedis)		[42]
Hemisyntrachelus	H. oligodon	Sud-Sacaco	A skull	An orca relative		[16]
Incakujira	I. anillodefuego	Aguada de Lomas	A preserved skeleton	A small rorqual (Balaenopteridae)		[21][43]
	I. fordycei	Aguada de Lomas	A preserved skeleton
Kogia	K. danomurai	Sacaco	A partial skull consisting of partial cranium, preserving the facial and dorsolateral regions of the cranial vault, but lacking most of the rostrum and basicranium	Basal member of Kogia, the genus of pygmy and dwarf sperm whale		[44]
Koristocetus	K. pescei	Aguada de Lomas	A partial skull	A small kogiid		[45]
Livyatan	L. melvillei	Cerro Colorado	A partially preserved skull with teeth and lower jaw	A very large raptorial physeteroid with 36 centimetres (1.18 ft) teeth		[5]
Lomacetus	L. ginsburgi	Aguada de Lomas		A porpoise relative (Phocoenidae)		[21][46]
Mamaziphius	M. reyesi	Cerros la Mama y la Hija	A partial skull consisting of partial cranium lacking most of the rostrum, the zygomatic processes of the squamosal, the occipital condyles and the ear bones	An early beaked whale (Ziphiidae)		[47]
Messapicetus	M. gregarius	Cerro Colorado	A partial skeleton consists of a skull, mandibles, humeri, vertebrae, and scapula	An early beaked whale (Ziphiidae)		[48]
Mesokentriodon	M. protohumboldti	Santa rosa	A sub-complete cranium, which lacks part of the right orbit, part of the basicranium, the ear bones, and teeth	A kentriodontid dolphin.		[49]
Miocaperea	M. pulchra	Aguada de Lomas	A partial skull	A cetothere whale		[50]
Ninoziphius	N. platyrostris	Sacaco	A partial skeleton	A giant beaked whale-relative		[16]
Odobenocetops	O. leptodon	Sacaco	A preserved skull	A tusked odontocete belonging to its unique family		[6]
	O. peruvianus	Sacaco	A partial skull
Piscobalaena	P. nana	Sud-Sacaco	A skull	A small cetothere		[16][18]
Piscocetus	P. sacaco	Sacaco	A partial skeleton	An extinct cetacean		[20]
Piscolithax	P. aenigmaticus	Aguada de Lomas	A partial skeleton	A porpoise relative (Phocoenidae)		[16][21]
Platyscaphokogia	P. landinii	Cerro Hueco la Zorra,	An incomplete skull lacking the tip of the rostrum and the basicranium.	An early beaked whale (Ziphiidae)		[51]
Pliopontos	P. littoralis	Sud-Sacaco	A partial skull	An early oceanic dolphin (Delphinidae)		[16]
Scaphokogia	S. cochlearis	Aguada de Lomas		An extinct kogiid		[21][52]

Seals

Taxa	Species	Locality	Material	Description	Images	Notes
Acrophoca	A. longirostirus	Sub-Sacaco	A partial skull.	Archaic southern seal (Monachinae)		[16]
Australophoca	A. changorum	Aguada de Lomas	A partial skeleton consists of incomplete right ulna, right radius, right and left humeri, and other unidentified remains.	A phocidae seal.		[21]
Hadrokirus	H. martini	Sub-Sacaco	A partial skull	Archaic southern seal (Monachinae)		[16][53]
Hydrarctos	H. lomasiensis	Sub-Sacaco	A skull.	A sea lion and fur seal relative (Otariidae)		[16]
Icaphoca	I. choristodon	Cerro La Bruja	A subcomplete skull with associated left and right mandibles, atlas, axis, third, fourth, and fifth cervical vertebrae.	Archaic southern seal (Monachinae)		[54]
Magophoca	M. brevirostris	Cerro la Bruja	A partial skeleton of a male.	Archaic southern seal (Monachinae)		[55]
Piscophoca	P. pacifica	Sub-Sacaco	A partial skull	Archaic southern seal (Monachinae)		[18]

Sloths

Taxa	Species	Locality	Materials	Description	Images	Notes
Thalassocnus	T. antiquus	Aguada de Lomas	A partial skeleton including the skull, mandible, and most of the postcranial skeleton.	a semi-aquatic giant sloth inhabiting marine environments		[4][16] [22][20] [56]
	T. carolomartini	Sacaco	An associated skull and mandible and two articulated hands, probably belonging to the same individual.
	T. littoralis	Sud-Sacaco	A skull with missing jugals.
	T. natans	Sud-Sacaco	A skull, mandible, and partial skeleton.