The mammalian order Cetacea is divided into three suborders: (1) Oligocene to Recent Odontoceti or 'toothed whales'— living today; (2) Oligocene to Recent Mysticeti or 'baleen whales'— living today; and (3) older and more primitive Eocene Archaeoceti or 'archaic whales'— which evolved from land mammals and gave rise to later odontocetes and mysticetes. My research on the origin and early evolution of whales is focused on archaeocetes. I have been fortunate to work with many colleagues on this in Egypt, Jordan, Pakistan, and India, (see co-authors in the publication list below). The stages of early whale evolution that we have documented are shown here in Figure 1. We have found and collected virtually complete skeletons of middle-to-late Eocene Basilosauridae (Dorudon and Basilosaurus), exceptionally complete skeletons of middle Eocene Protocetidae (especially Rodhocetus and Artiocetus), and a partial skull of earliest middle Eocene Pakicetidae (Pakicetus). Recovery of diagnostic ankle bones in the skeletons of primitive protocetids during our field work in Pakistan in 2000 confirmed their derivation from Artiodactyla (the mammalian order including cows, deer, hippos, etc.), and showed convincingly that whales did not originate from mesonychid condylarths as Van Valen hypothesized (and we had expected).
Figure 1. Skeletons of the archaeocetes Dorudon atrox and Rodhocetus balochistanensis compared to that of Elomeryx armatus, which is here taken as a model for the extinct group of artiodactyls (Anthracotheriidae, s.l.) that we now think may have given rise to archaic whales. Pakicetus has a distinctive skull and lower jaw, but is not demonstrably different from early protocetids postcranially. Note changes in body proportions and elongation of feet for foot-powered swimming in Rodhocetus, then later reduction of the hind limbs and feet as the tail-powered swimming of modern cetaceans evolved in Dorudon.
A. Elomeryx drawing from W. B. Scott, first published in 1894. B. Pakicetus skull from Gingerich et al. (1983). Terrestrial interpretation is pure speculation: what little is known of the skeleton resembles Rodhocetus. C. Rodhocetus skeletal reconstruction from Gingerich et al. (2001). D. Dorudon skeletal reconstruction from Gingerich and Uhen (1996). Figure may be reproduced for non-profit educational use.
Field work in Pakistan was initiated in 1975 to investigate sites previously reported as yielding Eocene land mammals. This led to the suggestion that some fossils there interpreted as mesonychids might really be archaeocetes (Gingerich, 1977). Our 1977 field work in marine strata yielded more archaeocetes, which, foolishly, we were not very interested in at the time (Gingerich et al., 1979). Pelvic bones that we found that year in the Sulaiman Range were attributed, questionably, to land mammals, because it was impossible to imagine that whales had such robust hind limbs. In the field we joked that these might be 'walking whales', but the idea seemed preposterous because there were no whales known then that were primitive enough to have walked. Our first important contribution was discovery of the remains of a new archaeocete, Pakicetus inachus, in the late 1970s. Pakicetus, known only from the skull and lower jaw, was then the oldest known archaeocete (Gingerich et al., 1983— this distinction now belongs to Himalayacetus; see Bajpai and Gingerich, 1999).
In the 1980s our field work on archaeocetes shifted to Egypt, to the classic but long-neglected site of Zeuglodon Valley or, today, Wadi Hitan. Our camp in the desert in Wadi Hitan is shown in Figure 2, and investigation of a weathered Basilosaurus is shown in Figure 3. Our most interesting discovery came in 1989, when we found that both Basilosaurus isis and Dorudon atrox retained feet and toes (see Figs. 4 and 5). This discovery then led to renewed investigation of middle Eocene whale strata in Pakistan, starting in 1991, and focusing on on the Sulaiman Range where we had earlier joked about 'walking whales'.
New whales named from Wadi Hitan and Fayum Province in Egypt include Ancalecetus simonsi (Gingerich and Uhen, 1996) and Saghacetus osiris (see Gingerich, 1992).
Figure 3. Dr. B. Holly Smith working at the base of the tail of a weathered Basilosaurus isis in Wadi Hitan, Egypt. We were particularly interested in this part of the skeleton because this is where the reduced hind limbs, feet, and toes were found (see Fig. 4). Photograph ©1991 Philip Gingerich. Figure may be reproduced for non-profit educational use.
Figure 4. Ankle, foot, and toes of Basilosaurus isis excavated in Wadi Hitan, Egypt. This find was described in Gingerich et al. (1990). The foot as shown is approximately 12 cm long. Photograph ©1991 Philip Gingerich. Figure may be reproduced for non-profit educational use.
Our first important find when we returned to Pakistan in the 1990s was an unusually complete skeleton that we named Rodhocetus kasranii (Gingerich et al., 1994). This came from the flank of the Rodho ('bald') part of the Zinda Pir anticlinorium on the east side of the Sulaiman Range. Rodhocetus is interesting and important in having a large pelvis connected to the vertebral column, but the sacral vertebrae in this connection are no longer completely fused, and Rodhocetus kasranii appears to be an intermediate showing how the sacrum became disarticulated to make the back flexible as it is in tail-powered swimmers like Dorudon and later whales. The femur is preserved on one side of the original Rodhocetus kasranii skeleton, but with this exception, the forelimbs are missing, the hind limbs are missing, and most of the tail is missing.
Continued work on the east side of the Sulaiman Range in Pakistan yielded many additional archaeocetes, including Takracetus simus, Gaviacetus razai, Dalanistes ahmedi, Qaisracetus arifi, Andrewsiphius sloani, Babiacetus indicus, Basilosaurus drazindai, and Basiloterus hussaini (Gingerich et al., 1995, 1997, 2001). However, these specimens generally lack forelimbs, hind limbs, and tails. Our inability to find limbs and tails was so frustrating that in 2000 we moved from this area, where fossil-bearing strata are beautifully exposed, to the west side of the Sulaiman Range in Balochistan Province. Previously, no fossil whales had been found on the west side of the Sulaiman Range, and the strata that interest us are not nearly so well exposed there (Fig. 6).
We have had very good luck finding well-preserved archaeocetes on the west side of the Sulaiman Range in Pakistan. The most notable were described and named Artiocetus clavis and Rodhocetus balochistanensis (Figs. 7-8; see Gingerich et al., 2001). These are the first early archaeocetes to preserve ankle bones in association with skulls and skeletons, and the first to show that early whales had distinctively artiodactyl-like ankles. Thus the earlier idea that whales evolved from mesonychid condylarths is no longer tenable and we expect that the ancestor was instead something like an anthracotheriid artiodactyl (e.g., Elomeryx in Fig. 1). From the point of view of the fossil record, the 'sister-group' relationship of whales and hippos promoted by molecular phylogeneticists is now plausible, though still tenuous and unproven.
Combining what we know of the skeletons of Rodhocetus kasranii and Rodhocetus balochistanensis, it is possible to make a composite restoration of the latter, which is the reconstruction shown in Figure 1C.
Figure 7. Cranium of middle Eocene protocetid archaeocete Artiocetus clavis from Pakistan, shown in dorsal view. Note the excellent preservation, external nares opening less than 10 cm from the front of the skull, and the relatively narrow frontal shield separating the orbits. Ankle bones of this specimen are shown at right in Fig. 8. Scale is in cm (10 cm total). Photo ©2001 Philip Gingerich. Figure may be reproduced for non-profit educational use.
Figure 8. Ankle bones of middle Eocene protocetid archaeocetes Rodhocetus balochistanensis (left) and Artiocetus clavis (right) from Pakistan, compared to those of the pronghorn Antilocapra americana (center). Note double-pulleyed astragalus, notched cubloid, and prominent fibular facet on the calcaneum (not preserved in Artiocetus), which are characteristic of mammals of the order Artiodactyla. These fossil specimens, preserved as parts of associated skulls and skeletons of protocetid archaeocetes, show that early whales shared a common ancestry with artiodactyls. Skull of the Artiocetus specimen is shown in Fig. 7. Scale is in cm. Photograph ©2001 Philip Gingerich. Figure may be reproduced for non-profit educational use.
As outlined above, we worked at Wadi Hitan in Egypt from 1983 through 1993, and collected several unusually complete skeletons of 5-meter-long Dorudon atrox. We mapped many skeletons of the 18-meter-long serpentine Basilosaurus isis, but never had the resources to collect a skeleton. Attempts to interpret Basilosaurus have long been frustrated because no one ever collected a complete skeleton anywhere. The classic Basilosaurus cetoides from Alabama restored by Gidley, 1913, and Kellogg, 1936— on exhibit at the Smithsonian Institution in Washington, D.C.— is a composite of two partial skeletons with important parts missing or borrowed from other marine mammals.
Figure 9. Skeletal restoration of 17-meter or longer fossil whale Basilosaurus cetoides from Alabama published by Gidley (1913). I prefer this restoration to that of Kellogg (1936) because it looks more lifelike. The true length of the skeleton is unknown because it is a composite of two partial skeletons. Pelvis and femur here have been modified to resemble those of Basilosaurus isis described from Egypt (Gingerich et al., 1991; see above). Figure may be reproduced for non-profit educational use: credit Gidley (1913).
Study of Basilosaurus took a major step forward in 2005 when an important skeleton of B. isis was collected in Wadi Hitan. Later the same year, Wadi Hitan was declared a UNESCO World Heritage Site because of its natural beauty and importance for understanding whale evolution. By prearranged agreement, the new Basilosaurus skeleton is to be prepared, studied, and then returned to Egypt for exhibition. The skeleton is expected to play an integral role in the educational development of Wadi Hitan.
Figure 10. Wadi Hitan site of Basilosaurus isis fossil whale skeleton excavated in 2005, western Fayum Province, Egypt. Basilosaurus lived in late Eocene times, about 40 million years before present, in a shallow sea called Tethys that covered much of northern Egypt. Now the ancient sea bed is exposed at the desert surface and it is slowly being eroded by the wind. Wadi Hitan is a protected area administered by the Egyptian Environmental Affairs Agency. It is a popular tourist destination because of its natural beauty and its extraordinary abundance of fossil whales and other marine life. Wadi Hitan is accessible by desert track through Fayum and Wadi Rayan. Photograph ©2005 Philip Gingerich. Figure may be reproduced for non-profit educational use.
Figure 11. Basilosaurus isis fossil whale skeleton excavated in Wadi Hitan, Egypt, in 2005. Excavation of the fossil skeleton was carried out by the University of Michigan Museum of Paleontology and the Egyptian Environmental Affairs Agency, working together to enable study of this unusual whale and to make it available for museum exhibition in Egypt and elsewhere. The skull of this specimen was excavated in 1989 by a University of Michigan - Duke University - Egyptian Geological Survey team. The skull was collected from the foreground of the photograph, and it is presently on exhibit in the University of Michigan Exhibit Museum. Photograph ©2005 Philip Gingerich. Figure may be reproduced for non-profit educational use.
Figure 12. Basilosaurus isis fossil whale skeleton excavated in Wadi Hitan, Egypt, in 2005. This photo shows how a fossil skeleton is divided and enclosed in burlap-and-plaster jackets for transportation to a museum for preparation. This Basilosaurus skeleton weighed 2,500 kg when it was ready for shipment. Photograph ©2005 Philip Gingerich. Figure may be reproduced for non-profit educational use.
Figure 13. Phylogeny of Cetacea showing a common ancestry shared with Artiodactyla, and the hypothesized evolutionary origin of both from older Paleocene age Condylarthra. Horizontal axis is arbitrary, while the vertical axis is geological time. Our 2000 discovery of distinctively artiodactyl-like double-pulley astragalus bones in articulated skeletons of early archaeocetes is the principal evidence linking whales and artiodactyls as shown here (see Gingerich et al., 2001). The evolutionary origin of both whales and artiodactyls is closely tied to the Paleocene-Eocene boundary, and the transition from archaeocetes to modern whales is related to climatic and ocean circulation changes at the Eocene-Oligocene boundary. Source: University of Michigan Museum of Paleontology. Figure may be reproduced for non-profit educational use.
|Figure 14. Artists' restorations of Pakicetus inachus (left) and Rodhocetus balochistanensis (right), as featured on the cover of Science. These accompanied articles by Gingerich et al. (1983) and Gingerich et al. (2001). The Pakicetus cover was painted by Karen Klitz of the University of Michigan Museum of Paleontology (now at U. C. Berkeley), and the Rodhocetus cover was drawn by John Klausmeyer of the University of Michigan Exhibit Museum. Based on what we know today, these animals were probably less different than shown here, and the hands and feet reconstructed for Pakicetus probably looked more like those now known for Rodhocetus. Covers ©American Association for the Advancement of Science.|
Figure 15. Field crew enjoying tea at the end of a productive day near Karkana in eastern Balochistan. Geological Survey of Pakistan geologists Munir ul-Haq and Mohammad Arif are at the left (red cap) and second from the right (white turban), respectively. University of Michigan graduate student Iyad Zalmout is standing. Remaining men are drivers and guards. Author is behind the camera. Photograph ©1999 Philip Gingerich. Figure may be reproduced for non-profit educational use.
Figure 16. University of Michigan and Egyptian Environmental Affairs Agency field crew in Wadi Hitan, western Fayum Province, Egypt, gathering as water is delivered to our desert camp. UM Ph.D. student Iyad Zalmout is in the blue 'gap' sweatshirt. EEAA ranger Mohamed Sameh is third from right, and EEAA ranger Gebaly Abu el-Khair is second from right. Author is behind the camera. Photograph ©2005 Philip Gingerich. Figure may be reproduced for non-profit educational use.
Gingerich, P. D. 1977. A small collection of fossil vertebrates from the middle Eocene Kuldana and Kohat formations of Punjab (Pakistan). Contributions from the Museum of Paleontology, University of Michigan, 24: 190-203. PDF (Deep Blue) or Request PDF/reprint 35
Gingerich, P. D., D. E. Russell, D. Sigogneau-Russell, J.-L. Hartenberger, S. M. I. Shah, M. Hassan, K. D. Rose, and R. H. Ardrey. 1979. Reconnaissance survey and vertebrate paleontology of some Paleocene and Eocene formations in Pakistan. Contributions from the Museum of Paleontology, University of Michigan, 25: 105-116. PDF (Deep Blue) or Request PDF/reprint 61
Gingerich, P. D. and D. E. Russell. 1981. Pakicetus inachus, a new archaeocete (Mammalia, Cetacea) from the early-middle Eocene Kuldana Formation of Kohat (Pakistan). Contributions from the Museum of Paleontology, University of Michigan, 25: 235-246. PDF (Deep Blue) or Request PDF/reprint 110
Gingerich, P. D., N. A. Wells, D. E. Russell, and S. M. I. Shah. 1983. Origin of whales in epicontinental remnant seas: new evidence from the early Eocene of Pakistan. Science, 220: 403-406. PDF or Request PDF/reprint 133
Gingerich, P. D., B. H. Smith, and E. L. Simons. 1990. Hind limbs of Eocene Basilosaurus isis: evidence of feet in whales. Science, 249: 154-157. Online or Request PDF/reprint 215
Gingerich, P. D. and D. E. Russell. 1990. Dentition of early Eocene Pakicetus (Mammalia, Cetacea). Contributions from the Museum of Paleontology, University of Michigan, 28: 1-20. PDF (Deep Blue) or Request PDF/reprint 220
Gingerich, P. D. 1992. Marine mammals (Cetacea and Sirenia) from the Eocene of Gebel Mokattam and Fayum, Egypt: stratigraphy, age, and paleoenvironments. University of Michigan Papers on Paleontology, 30: 1-84. PDF (Deep Blue) or Request PDF/reprint 243
Gingerich, P. D., S. M. Raza, M. Arif, M. Anwar, and X. Zhou. 1993. Partial skeletons of Indocetus ramani (Mammalia, Cetacea) from the lower middle Eocene Domanda Shale in the Sulaiman Range of Pakistan. Contributions from the Museum of Paleontology, University of Michigan, 28: 393-416. PDF (Deep Blue) or Request PDF/reprint 264
Gingerich, P. D. 1994. The whales of Tethys. Natural History Magazine, New York, 103(4): 86-89. PDF or Request PDF/reprint 272
Gingerich, P. D., S. M. Raza, M. Arif, M. Anwar, and X. Zhou. 1994. New whale from the Eocene of Pakistan and the origin of cetacean swimming. Nature, 368: 844-847. Online or Request PDF/reprint 274
Gingerich, P. D., M. Arif, and W. C. Clyde. 1995. New archaeocetes (Mammalia, Cetacea) from the middle Eocene Domanda Formation of the Sulaiman Range, Punjab (Pakistan). Contributions from the Museum of Paleontology, University of Michigan, 29: 291-330. PDF (Deep Blue) or Request PDF/reprint 303
Gingerich, P. D., M. Arif, M. A. Bhatti, H. A. Raza, and S. M. Raza. 1995. Protosiren and Babiacetus (Mammalia, Sirenia and Cetacea) from the middle Eocene Drazinda Formation, Sulaiman Range, Punjab (Pakistan). Contributions from the Museum of Paleontology, University of Michigan, 29: 331-357. PDF (Deep Blue) or Request PDF/reprint 304
Gingerich, P. D. and M. D. Uhen. 1996. Ancalecetus simonsi, a new dorudontine archaeocete (Mammalia, Cetacea) from the early late Eocene of Wadi Hitan, Egypt. Contributions from the Museum of Paleontology, University of Michigan, 29: 359-401. PDF (Deep Blue) or Request PDF/reprint 312
Gingerich, P. D., M. Arif, M. A. Bhatti, M. Anwar, and W. J. Sanders. 1997. Basilosaurus drazindai and Basiloterus hussaini, new Archaeoceti (Mammalia, Cetacea) from the middle Eocene Drazinda Formation, with a revised interpretation of ages of whale-bearing strata in the Kirthar Group of the Sulaiman Range, Punjab (Pakistan). Contributions from the Museum of Paleontology, University of Michigan, 30: 55-81. PDF (Deep Blue) or Request PDF/reprint 322
Gingerich, P. D., M. Arif, M. A. Bhatti, and W. C. Clyde. 1998. Middle Eocene stratigraphy and marine mammals (Cetacea and Sirenia) of the Sulaiman Range, Pakistan. Bulletin of Carnegie Museum of Natural History, 34: 239-259. PDF or Request PDF/reprint 328
Gingerich, P. D. and M. D. Uhen. 1998. Likelihood estimation of the time of origin of Cetacea and the time of divergence of Cetacea and Artiodactyla. Palaeontologia Electronica, 1(2): 45 pp. [ http://palaeo-electronica.org/1998_2/ging_uhen/issue2.htm]. Online or Request PDF/reprint 331
Gingerich, P. D. 1998. Paleobiological perspectives on Mesonychia, Archaeoceti, and the origin of whales. In J. G. M. Thewissen (ed.), Emergence of Whales: Evolutionary Patterns in the Origin of Cetacea, Plenum Publishing Corporation, New York, pp. 423-449. Order book or PDF or Request PDF/reprint 341
Luo, Z. and P. D. Gingerich. 1999. Terrestrial Mesonychia to aquatic Cetacea: transformation of the basicranium and evolution of hearing in whales. University of Michigan Papers on Paleontology, 31: 1-98. PDF (Deep Blue, 6-Mb) or Request PDF/reprint 356
Zalmout, I. S., H. A. Mustafa, and P. D. Gingerich. 2000. Priabonian Basilosaurus isis (Cetacea) from the Wadi Esh-Shallala Formation: first marine mammal from the Eocene of Jordan. Journal of Vertebrate Paleontology, 20: 201-204. Online or Request PDF/reprint 356
Uhen, M. D. and P. D. Gingerich. 2001. New genus of dorudontine archaeocete (Cetacea) from the middle-to-late Eocene of South Carolina. Marine Mammal Science, 17: 1-34. Online or Request PDF/reprint 363
Gingerich, P. D., M. Haq, I. S. Zalmout, I. H. Khan, and M. S. Malkani. 2001. Origin of whales from early artiodactyls: hands and feet of Eocene Protocetidae from Pakistan. Science, 293: 2239-2242. Online or PDF or Request PDF/reprint 381
Gingerich, P. D., M. Haq, I. H. Khan, and I. S. Zalmout. 2001. Eocene stratigraphy and archaeocete whales (Mammalia, Cetacea) of Drug Lahar in the eastern Sulaiman Range, Balochistan (Pakistan). Contributions from the Museum of Paleontology, University of Michigan, 30: 269-319. PDF (Deep Blue) or Request PDF/reprint 384
Gingerich, P. D. 2002. Progress on the origin of whales. Geoscience News, University of Michigan, Winter 2002: 7-11. PDF or Request PDF/reprint 387
Gingerich, P. D.. 2002. Whales that walked. LSA Magazine, University of Michigan, 2002: 25-27. PDF or Request PDF/reprint 389
Dolson, J. C., A. E. Barkooky, F. Wehr, P. D. Gingerich, N. Prochazka, and M. V. Shann. 2002. The Eocene and Oligocene paleoecology and paleogeography of Whale Valley and the Fayoum basins: implications for hydrocarbon exploration in the Nile Delta and ecoturism in the greater Fayoum Basin. AAPG International Conference and Exhibition, Guidebook for Field Trip 7, Cairo, 1-79 pp. PDF
Gingerich, P. D. 2003. Land-to-sea transition of early whales: evolution of Eocene Archaeoceti (Cetacea) in relation to skeletal proportions and locomotion of living semiaquatic mammals. Paleobiology, 29: 429-454. Online or Request PDF/reprint 405
Gingerich, P. D. 2003. Stratigraphic and micropaleontologic constraints on the middle Eocene age of the mammal-bearing Kuldana Formation of Pakistan. Journal of Vertebrate Paleontology, 23: 643-651. Online or Request PDF/reprint 408
Gingerich, P. D. 2004. Whale evolution. McGraw-Hill Yearbook of Science and Technology, 2004: 376-379. PDF or Request PDF/reprint 413
Gingerich, P. D. 2005. Cetacea. In K. D. Rose and J. D. Archibald (eds.), Placental mammals: origin, timing, and relationships of the major extant clades, Johns Hopkins University Press, Baltimore, pp. 234-252. Order book, PDF or Request PDF/reprint 432
Gingerich, P. D., I. S. Zalmout, M. Haq, and M. A. Bhatti. 2005. Makaracetus bidens, a new protocetid archaeocete (Mammalia, Cetacea) from the early middle Eocene of Balochistan (Pakistan). Contributions from the Museum of Paleontology, University of Michigan, 31 (9): 197-210. PDF (Deep Blue) or Request PDF/reprint 439
Clementz, M. T., A. Goswami, P. D. Gingerich, and P. L. Koch. 2006. Isotopic records from early whales and sea cows: contrasting patterns of ecological transition. Journal of Vertebrate Paleontology, 26: 355-370. Online or Request PDF/reprint 446
Gingerich, P. D. 2007. Early evolution of whales: a century of research in Egypt. In J. G. Fleagle and Christopher C. Gilbert (eds.), Elwyn Simons: A Search for Origins, Springer, New York, pp. 107-124. PDF or Request PDF/reprint 471
Gingerich, P. D. 2007. Stromerius nidensis, new archaeocete (Mammalia, Cetacea) from the upper Eocene Qasr el-Sagha Formation, Fayum, Egypt. Contributions from the Museum of Paleontology, University of Michigan, 31: 363-378. PDF (Deep Blue) or Request PDF/reprint 472
Gingerich, P. D. 2008. Basilosaurus cetoides. Encyclopedia of Alabama, 1386: 1-3. Online or Request PDF/reprint 475
Gingerich, P. D., M. Haq, W. v. Koenigswald, W. J. Sanders, B. H. Smith, and I. S. Zalmout. 2009. New protocetid whale from the middle Eocene of Pakistan: birth on land, precocial development, and sexual dimorphism. PLoS ONE, 4 (e4366): 1-20. Online/PDF or Request PDF/reprint 487
Peters, S. E., M. S. Antar, I. S. Zalmout, and P. D. Gingerich. 2009. Sequence stratigraphic control on preservation of late Eocene whales and other vertebrates at Wadi al-Hitan, Egypt. Palaios, 24: 290-302. Online/PDF or Request PDF/reprint 488
Koenigswald, W. v. and P. D. Gingerich. 2009. Wale in der Wüste: Fossilbericht zum Weg der Wale vom Land ins Wasser. In N. Elsner, H.-J. Fritz, R. Gradstein, and J. Reidtner (eds.), Evolution: Zufall und Zwangsläufigkeit der Schöpfung, Wallstein Verlag, Göttingen, pp. 341-361. Request PDF/reprint 491
Gingerich, P. D. 2010. Cetacea. In L. Werdelin and W. J. Sanders (eds.), Cenozoic Mammals of Africa, University of California Press, Berkeley, pp. 873-899. Request PDF/reprint 502
Koenigswald, W. v. and P. D. Gingerich. 2010. Vom Land ins Meer-- Evolution der Wale. In G. Wefer and F. Schmieder (eds.), Expedition Erde: Wissenswertes und Spannendes aus den Geowissenschaften, MARUM Bibliothek: Verständliche Geowissenschaften, Bremen, pp. 284-291. Request PDF/reprint 519
Gingerich, P. D. 2006. Early whales Ichthyolestes and Pakicetus (Mammalia, Cetacea): terrestrial, aquatic, or both? Caveat emptor! (abstract). Journal of Vertebrate Paleontology, Abstracts of Papers, 26 (suppl. 3): 68. Abstract
Gidley, J. W. 1913. A recently mounted Zeuglodon [Basilosaurus] skeleton in the United States National Museum. Proceedings of the U. S. National Museum, Washington, 44: 649-654.
Kellogg, R. 1936. A review of the Archaeoceti. Carnegie Institution of Washington Publications, 482: 1-366.
Uhen, M. D. 2004. Form, function, and anatomy of Dorudon atrox (Mammalia, Cetacea): an archaeocete from the middle to late Eocene of Egypt. University of Michigan Papers on Paleontology, 34: 1-222. PDF (Deep Blue: 66-Mb)
This research has been funded by the U. S. National Science Foundation, the National Geographic Society, and the University of Michigan. Any opinions, findings, and conclusions or recommendations expressed on this web page are those of the author and do not necessarily reflect the views of the National Science Foundation, the National Geographic Society, or the University of Michigan.