Kuldana Formation

Kuldana Formation
Stratigraphic range: Lutetian PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Unit of	Subathu Group
Underlies	Kohat Formation
Overlies	Ghazij, Shekhan & Chorgali Formations
Location
Location	Gilgit-Baltistan and Punjab, Pakistan
Coordinates	33°43′N 72°10′E / 33.717°N 72.167°E / 33.717; 72.167
Approximate paleocoordinates	14°18′N 68°42′E / 14.3°N 68.7°E / 14.3; 68.7
Region	Kala Chitta Range
Country	Pakistan
Type section
Named for	Kuldana Village, Hazara District[1]
Named by	Latif
Year defined	1970
Kuldana Formation (Pakistan)

The Kuldana Formation is a fossil-bearing geological formation of Lutetian (Early Eocene) age which crops out in northern Pakistan. The abundant fossil remains were deposited by rivers and estuaries crossing an arid to semi-arid environment, between several marine transgressions. Its fossil fauna is best known for the early cetaceans Indohyus, Pakicetus and Ambulocetus, that helped to shed a new light on the evolution of whales, but it also features a large number of early ungulates, rodents and primates.

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Fossils from the Kuldana Formation have been studied since long before the name was established, with some of the earliest papers being those of Pilgrim, published in 1940. At that point in time, the sediments were known as the Chharat beds. The name Kuldana Formation as such was first coined by Mir Abdul Latif in 1970, prior to which the sediments had already been known as the Kuldana Beds and Kuldana Series, deriving its name from a nearby village. Around the same time, Meissner and colleagues studied similar outcrops near the village of Mami Khel, 200 km (120 mi) southwest of Kuldana, naming it the Mami Khel Clay. Although study began prior to the publication of Latif's work, this paper was not published until later. Several subsequent papers comparing the two generally agreed that they were synonyms and represented a single geological formation, that being the Kuldana Formation. A 1996 publication by Pivnik and Wells meanwhile used the name Mami Khel Formation and Maas et al. (2001) treated the two as distinct formations primarily based on their geographic separation through the Indus River while providing no other indicators in how the two differed. Other studies treating the two formations as distinct include Leinders (1999) and Thewissen (2001).^[1]

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Outcrops of the Kuldana Formation are found in the form of isoclinal folds across northern Pakistan's Kohat plateau and Potwar plateau. The Formation stretches from Barbora and Mami Khel at the western edge of the Kohat plateau to the name-giving locality of Kuldana at the eastern end of the Potwar plateau. Between these points are a variety of other localities as well, such as Chorlakki, located within the eastern-most Kohat plateau, as well as Lammidhan and Ganda Kas (Kala Chitta) at the western end of the Potwar plateau.^[1][2]

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While the stratigraphy within the Kuldana Formation is poorly understood, its relation to under- and overlying formations has been much better studied thanks to the succession being consistently visible across various localities. At Banda Daud Shah, the Kuldana Formation overlies the Ghazij Formation, the Shekhan Formation and the Jatta Gypsum. The Ghazij and Shekhan Formations also underlie the Kuldana Formation at Chrolakki while at Ganda Kas and Gali Jhagir the formation preceding the Kuldana was the Chorgali Formation. The Kohat Formation consistently overlies the Kuldana Formation.^[1][2]

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The age of the Kuldana Formation has been subject to repeated revision and multiple back and forths among researchers. Two early estimates, proposed by Cotter and Pilgrim respectively, suggested that the Kuldana Formation was either Ypresian (Early Eocene) or Lutetian (early Middle Eocene) in age, with subsequent authors generally following one of these hypothesis. After officially establishing the name Kuldana Formation, Latif suggested that the formation dates to the lower to middle Eocene on the basis of shallow benthic foramins, somewhat straddling the line between both the results of Cotter and Pilgrim. This would come to be the general result of subsequent papers as well, which often recovered an age within that general range.^[1]

In 1983 Gingerich used the fact that the Kuldana Formation is preceded and followed by marine strata to compare it with then available maps of sea levels during the Eocene, arguing for a late Early Eocene age, once again falling into the convention established by prior work. Gingerich did however come to revise his 1983 age estimate in a paper published in 2003 that dealt with the stratigraphy observed across different localities in order to obtain a more reliable result. Another aim of this work was to provide counter arguments to some claims made around the turn of the century, when several papers claimed that the sediments at Mami Khel represented a distinct formation that dated to the early Early Eocene. To do so, foramins of underlying formations were used to establish a maximum age for the Kuldana strata. At Banda Daud Shah, Gingerich recovered a late Early Eocene to early Middle Eocene (P9 or P10) age based on the planktonic foraminifera of the underlying Shekhan Formation, with similar results being recovered based on shallow benthic foramins at Chorlakki, Ganda Kas and Gali Jhagir (all dated to SB12 to SB13). Gingerich further utilizes updated knowledge on global sea levels to find similar results. Unlike in 1983, Gingerich now recognized two distinct periods of low sea levels, one during the late Early Eocene and a second, longer-lasting period during the early Middle Eocene. Gingerich argues that, since only one terrestrial phase is observed within the stratigraphy of Eocene Pakistan, it is likely that the Kuldana Formation represents the longer period of low sea levels, placing it within the early Late Eocene.^[1]

The Kuldana Formation featured several different environments across its time of deposition, with the oldest layers showing fluvial conditions. The strata overlying these sediments suggest that the environment shifted to a mix of freshwater and shallow marine habitats, which is supported by multiple lines of evidence. Evidence for freshwater biomes is present through isotopic analysis as well as the local fauna, for example the freshwater snail Planorbis, whereas the presence of sharks and pycnodontoid fish shows the presence of marine habitats. It is thought that the archaeocetes that inhabited the formation at the time stuck to freshwater biomes, even if some localities were evidently closer to the coast.^[3]

This mix of fresh- and saltwater habitats was eventually followed by a marine transgression that characterizes the geology of the uppermost layers of the formation.^[3]

Fossiliferous sediments in and around the Ganda Kas localities were deposited in semi-arid Eocene floodplains and freshwater channels. The H-GSP Locality 62, from which an abundance of material is known, was deposited in a stillwater environment, while other localities in the area represent the remains of prehistoric rivers. Localities around Ganda Kas deposited in a marine environment appears to be of a later age.^[4]

Like in Ganda Kas, the depositional environment in the areas presenting a Banda Daud Shah-type fauna, such as the eponymous Banda Daud Shah and Barbora Banda localities, represents an arid environment crossed by various rivers. The most common fossil mammals are the early artiodactyl Diacodexis pakistanensis and the tapiroid perissodactyl Karagalax mamikhelensis ; the presence of adapids and arctocyonids in the area indicates that it probably had an older age than the Ganda Kas fauna.^[4]

Name	Species	Locality/Member	Material	Notes	Image
Ambulocetus[3][5]	A. natans	H-GSP Loc. 9209 & 9204	Several specimens.	An ambulocetid cetacean.
Artiodactyla indet.[6]		Chorlakki	An astragalus and two calcaneum	These fossil remains are thought to be too large and robust to have belonged to the Chorlakki dichobunids or Indohyus.
Attockicetus[3][5]	A. praecursor	H-GSP Loc. 9204 H-GSP Loc. 9607, Shepherd's Lake	An incomplete cranium, worn teeth, premolars.	A remingtonocetid cetacean.
	Cf. A. sp.	H-GSP Loc. 9607, Shepherd's Lake	Two teeth	A remingtonocetid cetacean.
Basilosauridae indet.[7]		Ganda Kas	Two isolated teeth.	One of the teeth resemble those of Ichthyolestes.
Chorlakkia[6]	C. hassani	Chorlakki	A left dentary and multiple teeth	A dichobunid.
Dichobunidae indet.[6]		Chorlakki	Teeth	Teeth distinct from the other known Kuldana dichobunids. One particular tooth might represent a hyopsodontid.
Dulcidon[8][9][5]	D. gandaensis	Ganda Kas & Chorlakki	Two right molar.	A dichobunid
Gandakasia[3][7]	G. potens	H-GSP Loc. 58, Ganda Kas H-GSP Loc. 9607 Shepherd's Lake	A fragmentary mandible	A protocetid cetacean
Gobiohyus[7][6][4]	cf. G. orientalis	Ganda Kas	A single tooth.	An helohyid.
Gujaratia[6][4][10][11]	G. pakistanensis	Chorlakki Lammidhan Barbora Banda I & II H-GSP Loc. 300, 9710 & 9712, Banda Daud Shah	Teeth	A diacodexeid. Gujaratia is rare at Chorlakki and may be the only artiodactyl at Barbora Banda. Formerly classified within the European and American genus Diacodexis.
Ichthyolestes[3]	I. pinfoldi	H-GSP Loc. 62, Ganda Kas	A single molar	A pakicetid.
Indohyus[6]	I. indirae	Ganda Kas, Chorlakki & Kalakot	Numerous specimens	A raoellid. The most abundant artiodactyl at Kalakot, but less common at Chorlakki where Khirtharia is more prominent.
	I. major	Chorlakki	An isolated tooth	A larger species of raoellid, that would reach about twice the size of I. indirae, but might also represent an unrelated species of diacodexeid or dichobunid.
Khirtharia[7][6][4]	K. dayi	Chorlakki, Kalakot & Panoba H-GSP Loc. 62, Ganda Kas	Fragments of maxilla and mandibles ; isolated teeth	A large helohyid. Khirtharia is the must abundant artiodactyl at Chorlakki and more common than Indohyus, but the reverse is seen at Kalakot.
Nalacetus[3][5]	Nalacetus ratimitus	H-GSP Loc. 62, Ganda Kas	Fragments of palate, maxilla and teeth	A pakicetid cetacean
Pakibune[6]	P. chorlakkiensis	Chorlakki & Lammidhan	Teeth	A moderately sized dichobunid, larger than the other dichobunid taxa from the formation.
Pakicetus	P. attocki[7]	H-GSP Loc. 62, Ganda Kas	Complete cranial remains.	A pakicetid cetacean
	P. calcis[3]	H-GSP Loc. 9607 Shepherd's Lake H-GSP Loc. 9607, Valley E	A partial mandible, palate fragment and teeth	A pakicetid cetacean
	P. chittas[3]	Chorlakki H-GSP Loc. 9607, Shepherd's Lake	Fragments of mandibles	A pakicetid cetacean
	P. inachus[6][12]	Chorlakki	A partial skull, mandible and teeth	A pakicetid cetacean
Protocetidae indet.[7]		Ganda Kas	Jaw fragment and two isolated teeth	One of the teeth resemble those of Ichthyolestes.

Name	Species	Locality/Member	Material	Notes	Image
Anthracobune[11][10][16][17]	A. pinfoldi[7]	Upper Member : Lammidhan & Ganda Kas	Relatively complete cranial remains and isolated teeth.	The largest anthracobunid in the formation.
	A. wardi[6]	Chorlakki & Ganda Kas	Several mandibles, fragments of a skull and isolated teeth.	An anthracobunid. Formerly the distinct genus Lammidhania, also present in the Subathu Formation. Includes the holotype of Pilgrimella pilgrimi.
"Forstercooperia"[6]	"F." jigniensis	Chorlakki	Teeth	A paraceratheriid.
Isectolophidae indet.[6]		Chorlakki	A tooth
Jozaria[11][16]	J. palustris	Upper Member	Several teeth	An anthracobunid.
cf. Kalakotia[4]	K. sp.	H-GSP Loc. 62, Ganda Kas H-GSP Loc. 9613, Thatta	A fragmentary maxilla and isolated teeth	A lophialetid tapiroid, probably representing a new species.
Karagalax[18]	K. mamikhelensis	H-GSP Loc. 300, Barbora Banda	Several relatively well-preserved skulls ; isolated postcranial elements tentatively referred to the genus.	An isectolophid tapiromorph, more cursorial than its contemporary American relatives.
Obergfellia[6][11]	O. occidentalis	Ganda Kas	Several mandibles.	An anthracobunid. Includes most of the material formerly assigned to Pilgrimella pilgrimi.
Palaeosyops[6][7][4][19]	P. dayi	Chorlakki H-GSP Loc. 64, 9613 and 227, Ganda Kas & Thatta	Fragmentary maxilla and mandible ; isolated teeth	Formerly belonging to the genus Eotitanops, it seems to be intermediate between the two genera. A small and primitive brontothere. Also present in the Baska Formation.
Pakotitanops[7][4]	P. latidentatus	H-GSP Loc. 9205 & 9206, Ganda Kas	A fragmentary maxilla and isolated teeth	A brontothere, distinctly larger and more derived than Eotitanops.