The Emergence of Whales, Chp. 1
Chapter 1: Synopsis of the Earliest Cetaceans: Pakicetidae, Ambulocetidae, Remingtoncetidae, and Protocetidae
Author: Ellen M. Williams, Department of Anatomy, Northeastern Ohio Universities College of Medicine, Rootstown, OH 44272
Quote from the first paragraph:
“These discoveries have helped to document an extraordinary progression in whales from a predatory terrestrial ancestor to highly specialized open marine dwellers.”
Originally one family, now four.
Most of the recent discoveries have come from India and Pakistan. With each description, Williams provides the geological setting. Rather than do it whale by whale, I’ll give them here. There will be more on what they are later.
The cast of characters (description date following)
– Pakicetidae – Pakicetus inachus (1981) Pakicetus attocki (1980) Ichthyolestes pinfoldi (1958) Nalacetus ratimitus (1998 – keep this one in mind!)
– Ambulocetidae –
– Remingtoncetidae –
– Protocetidae –
The amount of fossil material is described for each one. Some skeletons are partial, other species are primarily based on teeth or vertebrae. There are a lot of teeth (one chapter of the book is exclusively about archaeocete teeth)
( The symbol ‘=?’ means ‘implies’)
Pakicetids: redbeds of the lower Kuldana Formation lower Kuldana consists of red mudstones, and limestones, sandstones, and conglomerates. Lithofacies interpreted as floodplain soil nodules reworked in river channels during episodic channel incision. =? pakicetids inhabited fluvial environments.
Ambulocetids: upper Kuldana formation upper Kuldana consists of interbedded shales, marls and limestones with minor evaporites. lower/upper transition marked by variegated shales interpreted as freshwater deposits. An extensive tidal sequence deposited in an arid environment. =? Ambulocetids occupied tidal areas with a strong freshwater influence.
Remingtoncetids: Domanda and Harudi formations (Earliest in Kuldana-Kohat formation, interbedded thin argillaceous limestones and calcareous shales, featuring nummulites, bivalves and gastropods. Similar to tidal coastal environment of ambulocetids.)
Domanda and Harudi are interbedded red-brown and green shales, silty marls, thin oyster-rich limestones. Interpreted as offshore shallow marine to distal carbonate-rich environments. =? differentiation of environment between remingtoncetids and protocetids ??? More certain, remingtoncetids and protocetids occupied coastal marine waters with some freshwater influence.
Protocetids: Mokattam formation (also Guishi, Maadi) and Blue Bluff unit Mokattam: shallow carbonate platform environment (nummulitic limestone, with some mollusks, bryozoans, and echinoids), regressional. Clearest association with shallow marine offshore shelf deposition.
Blue Bluff is sandy mudstones, oyster-rich marls, Santee limestone is marls and purer carbonates. Represents a shallow nearshore marine environment, potentially tidal. =? protocetids also inhabited shallow nearshore and shallow offshore environments.
This page was last updated September 1, 2001.