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Oceans of Kansas: A Natural History of the Western Interior Sea

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Revised, updated, and expanded with the latest interpretations and fossil discoveries, the second edition of Oceans of Kansas adds new twists to the fascinating story of the vast inland sea that engulfed central North America during the Age of Dinosaurs. Giant sharks, marine reptiles called mosasaurs, pteranodons, and birds with teeth all flourished in and around these shallow waters. Their abundant and well-preserved remains were sources of great excitement in the scientific community when first discovered in the 1860s and continue to yield exciting discoveries 150 years later. Michael J. Everhart vividly captures the history of these startling finds over the decades and re-creates in unforgettable detail these animals from our distant past and the world in which they lived—above, within, and on the shores of America’s ancient inland sea.

459 pages, Kindle Edition

First published July 1, 2005

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Michael J. Everhart

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Displaying 1 - 30 of 32 reviews
Profile Image for Mike Renz.
51 reviews
June 25, 2021
The "flat space" between the Appalachian Mountains and the Rocky Mountains is both over looked and a mystery to most folks, including geologists. I believe it was the legendary paleontologist Anita Harris who said you can "do the geology of Midwest at 70 mhp". Dr. Harris was rarely wrong about much, but in this case, she is.

I bought and read this book as part of an effort to develop a better conceptual model of the Great Plains. Paleontology can be brutally boring. Its the "biology of the dead". However Michael Everhart puts the meat back on the bones and brings the long dead back to life. For me, he also brings back the interior sea and presents it in a way that is easy to imagine and understand.

The best part of reading this book is that it makes you realize just how diverse and remarkable life on Earth is.
Profile Image for Joey Miller.
186 reviews6 followers
August 13, 2025
An excellent overview of the fossil biodiversity of the western interior seaway, including a detailed history of discoveries throughout, and also a fun read since I know who the author is. This is more of a coffee table book than a true reference book, but it has tons of helpful info and pictures for anyone with actual experience fossil hunting in this area (as I do). I imagine it would be somewhat drier for anyone reading it that hasn't found a lot of the fossils that are discussed. Something that did stand out as I read this is the tenuous nature of scientific knowledge, as what is considered accurate biographical information on these animals has changed many many times over the years, and sometimes drastically. "Scientist's current best guess," is probably a better way to read the information, rather than true fact
Profile Image for Tim Martin.
872 reviews53 followers
May 16, 2023
Beautifully illustrated, thoroughly researched, and very accessible popular and academic work on when Kansas was covered by an ocean. Specifically, it is on a 5-million-year span of time during the Late Cretaceous, the time when the Smoky Hill Chalk was deposited on the bottom of the Western Interior Sea, roughly 87-82 million years ago. This chalk is accessible in many locations in Kansas and is the most thoroughly studied of any period of the Cretaceous in Kansas. The book chronicles the history of fossil collecting in the chalk (occurring since the late 1860s), the history of the study of the fossil organisms in the Smoky Hill Chalk, the animals that called the sea home (from invertebrates to reptiles and birds), what we know of conditions in the Western Interior Sea and how they changed over time, and what study of this region tells us about the wider Mesozoic world both before and after and in other areas of the world. The book is richly illustrated with black and white and mainly color photographs of fossils from the Smoky Hill Chalk and has a series of gorgeous color plates of various life reconstructions of the sharks, bony fish, birds, pterosaurs, and most of all marine reptiles of the Western Interior Sea, all by the amazing Dan Varner. Though the book is primarily on the Smoky Hill Chalk, the younger Pierre Shale is discussed some (as for instance, the first major Cretaceous fossil from Kansas and the type specimen of Elasmosaurus platyurus came from the Pierre Shale).

Chapter 1, the introduction, begins with a fictionalized account of a day in the life of a mosasaur in the Inland Sea, beginning a tradition for each subsequent chapter starting with a fictionalized depiction of the fish, reptiles, and birds of the Western Interior Sea. The chapter goes on to introduce the reader to general information on the Western Interior Sea (the water was probably less than 600 feet deep for instance, and the name of the chalk derives from the Smoky Hill River, which gets its name from the Smoky Hills in eastern Kansas, though the chalk itself is important in mostly the western third of Kansas).

Chapter 2, “On Discovery of the Western Interior Sea,” discusses the earliest days of fossil hunting in the Smoky Hill Chalk, beginning with the Lewis and Clark expedition in 1804 and goes on to discuss the Sternbergs, most particularly Charles H. Sternberg, the famous fossil hunter of the Smoky Hill Chalk, Cope and Marsh’s “Bone War” competitions for the marine fossils of Kansas, and closes with a discussion of early studies of biostratigraphy (a subject collectors decades paid little if any attention to for decades, with many times specimens lacking even good locality data).

Chapter 3, discusses invertebrate, plant, and trace fossils of the Western Interior Sea. Topics covered include the giant inoceramid clams of the ocean bottom (reaching diameters of 5 feet), what life was like on the sea bottom (often quite low in oxygen), the numerous leaf fossil imprints from the Dakota Sandstone of the early part of the Late Cretaceous, ammonites (their shells rarely occur in the chalk and most often only their impression remains), belemnites, squid (Tusoteuthis longus), colonial and free-living crinoids (the only echinoderms of the chalk, in genus Uintacrinus), fossilized pearls, coprolites (primarily from sharks and mosasaurs), and fossil wood, sometimes showing openings made by borings of Teredo clams.

Chapter 4 is on sharks. An important part of the chapter is how many bone fragments and other fossils from the Smoky Hill Chalk show evidence of shark predation or scavenging in terms of bite marks, broken tips of embedded shark teeth, and/or weathering showing that the bone was at least partially digested by a shark, perhaps later coughed up. Lots of photos of shark teeth fossils that are found in the Smoky Hill Chalk (at their greatest variety in the lower half of the formation), a discussion of “shark mummies” that were found, and the main species of sharks found such as the ginsu shark (Cretoxyrhina mantelli) and several species of ptychodontid sharks that most likely fed on clams and other hard-shelled prey due to their “pavement” toothed upper and lower jaws. Also, some discussion of the decline of sharks as mosasaurs increased in numbers, size, and diversity, a point revisited later on in the book as well.

Chapter 5 is on “Fishes, Large and Small,” with the star being the famed “fish within a fish” fossil, the nearly 14 foot long Xiphactinus audax fossil that died shortly after having swallowed Gillcus arcuatus, a fish about half its length, though other fishes are also discussed as well, such as fish of the family Saurodontidae, which had a predentary bone projecting forward from the lower jaw (perhaps used like the beak of a modern swordfish), Cimolichthys nephaholica, one of the more common species of fish preserved in the chalk and appears to have been a medium sized predator like a barracuda, and Protosphyraena gladius, a enormous filter feeder fish that was probably about 15 feet in length. The author noted that after shark teeth, fish fossils are the most common vertebrate fossils in the Smoky Hill Chalk and that perhaps 80 to 90% of the fossils seen in the field are fish (though as they are so common, are less often collected and make up about 60% of the fossils in museum collections).

Chapter 6 is on turtles, a group that was apparently heavily preyed upon and is most often known from skulls and isolated limb material or shell fragments, with most of the current research being done on turtles of genus Protostega. The famous and enormous Archelon is known to have existed in the Western Interior Seaway, but rocks of the age that could have contained their remains in Kansas were apparently exposed and eroded away millions of years ago. There is a nice discussion and illustration of a Protostega gigas turtle that was apparently killed but not consumed by a 30-foot Tylosaurus proriger.

Chapter 7 is on elasmosaurs, a wonderfully written chapter discussing the history of the discovery and study of them, elasmosaur gastroliths, the various types of plesiosaurs (the giant pliosaurids, extinct before the formation of the Smoky Hill Chalk, the short-necked polycotylids, and the extremely long-necked elasmosaurs), a fascinating discussion of how elasmosaurs moved and hunted, how they gave birth and possibly protected their young, and how thanks to the Late Cretaceous explosion of mosasaurs, may have been driven to the edge of extinction as mosasaur numbers and diversity increased.

Chapter 8 is on pliosaurs and polycotylids. I had heard of pliosaurs, but polycotylids were new to me and were fascinating to read about, once lumped in with all the other short-necked, large-headed pliosaurids, but beginning in the mid-1990s, it was determined (assuming it is correct according to the author) that Late Cretaceous short-necked pleisosaurs are more closely related to elasmosaurs than to the pliosaurids.

Chapter 9 is in some ways the heart of the book, the chapter the author in my opinion was the most passionate and knowledgeable about, and pretty much worth the price of admission, that being a chapter on mosasaurs (I think it is the longest chapter too). Mosasaurs 100 million years ago, just into the second half of the Cretaceous, went from shore dwellers to ocean dwellers and within a short amount of time evolved so they could no longer leave the water. Though hardly the first reptile of course to reenter the ocean, “they were probably the most successful in terms of their diversity, large numbers, and eventual domination of the marine environment,” and though they appeared to have caused the extinction or decline of several species of sharks and the decline of plesiosaurs and were so successful they appeared to be invading freshwater environments as well, they too for reasons unknown went extinct at the end of the Cretaceous along with the dinosaurs, plesiosaurs, and pterosaurs.

Lots to read in the chapter on mosasaurs, from the history of the discovery of the fossils and the study of these animals, discussion of locomotion, raising their young, their anatomy, ecology, how big they got (several lineages reaching more than 50 feet in length), how they were spreading and specializing throughout the world, and how some were adapted not to eat fish or anything else swimming they could catch but instead for crushing the hard shells of clams and other shellfish.

Chapter 10 is on “Pteranodons, Rulers of the Air,” with Pteranodon longiceps joining Tyloaurus proriger as signature fossils of not only the Smoky Hill Chalk but of Kansas as a whole, with both first discovered in Kansas and occurring mostly in Kansas and both (with the author’s help) becoming co-State Fossils in 2014. Though Pteranodon is the star, there is a good bit of discussion of Nyctosaurus with its bizarre head crests. Lots of discussion of the history of the fossils finds, their study, theories on how these animals flew, how they took off, what they ate (and what we know of what they ate thanks to fossil remains), and why their fossils would turn up in the middle of the ocean, hundreds of miles from land.

Chapter 11 is titled “Feathers and Teeth” and is on the toothed birds of the Smoky Hill Chalk, namely the flying (possibly diving too) Ichthyornis (“fish bird”) and the much larger and flightless and likely unable to go far at all on land, Hesperornis (“western bird”), a bird that successfully competed with the plesiosaurs, mosasaurs, fish, and sharks, though the author discusses how the fossil evidence shows they may have been more common in cooler, northern waters. There are brief mentions of other fossil birds, Baptornis advenus, Baptornis varneri (named after Dan Varner, the chief artist on display in the book), and Fumicollis hoffmani.

Chapter 12 is on the few dinosaur fossils known from the Smoky Hill Chalk, five sets of remains discovered since 1871, two of which are hadrosaur remains and the rest belong to nodosaurs, all discussed at length, with possibly the first two nodosaur specimens might actually belong to the same individual animal.

Chapter 13, “The Big Picture,” shows the Western Interior Sea and what it was like, all of its fauna, during the 5-million-year span of the Smoky Hill Chalk, with the author further breaking down what the fauna was like in three shorter periods, the late Coniacian (a period of about 1.2 million years), the entirety of the Santonian (about 2.3 million years), and the beginning of the Campanian (about 1.5 million years), with in charts and descriptive text the author noting the appearance and disappearance of species of clams, ammonites, squid, sharks, bony fish, the various marine reptiles, pterosaurs, and birds as well as noting general conditions of the ocean and of deposition conditions.

The final section of text is the epilogue, discussing what happened to the Western Interior Sea and the author discussing that while the Chicxulub impact may have been a factor in Mesozoic mass extinctions, he discusses for a few pages why he thinks it “would have happened anyway,” as “[w]hatever killed off the marine reptiles and the dinosaurs of the Late Cretaceous was a far more complex mix of environmental problems than just a big rock falling out of the sky,” noting in passing that the Manson impact, creating a crater 22 miles across, that occurred 10 million years before Chicxulub and caused some local devastation appears according to the author based on “the size and condition of the elasmosaur and the large number of other species that were collected (mosasaurs, fishes, invertebrates), it certainly appeared to me that life in the sea was back to normal” by the time of Chicxulub.

Following this is an extensive section of references and a thorough index. A few sections could get a little technical with the terms used to describe different bones or their appearance and structure and with the scientific names, but I was never lost. I found the style of writing engaging and really enjoyed the fictionalized accounts of life in the Western Interior Sea. The author also made the human story of fossil hunting and studying the fossils interesting and included a number of first-hand accounts of his and his colleague’s work out in the field and in museums. I loved how he showed many fossils revealed a lot about life in the Western Interior Sea by what in fact was fossilized and I also loved how he showed trends in study of the fossils and exciting new areas of research. The book is lavishly illustrated and probably is one of the finest popular paleontology books anywhere for color photos of a wide variety of marine fossils.
693 reviews
June 16, 2015
This is a well-written and interesting book exploring the extinct fauna and some of the geology of Kansas from when it was part of the Western Interior Sea. It is a little challenging in its use of scientific terminology like the many scientific names of animals and very specific (and for me unfamiliar) terms for periods of time and geologic stratigraphy. It was worth the challenge though, and all of that good information is framed in imaginative reconstructions of the life and death extinct fish, sharks, mosasaurs, and pteranodons. Perhpas even more enjoyable were the many stories of how the bones of these animals were discovered, classified, and argued over; much of this was due to a competition between two early paleontologists, O.C. Marsh and Edward Cope. There are plentiful pictures and illustrations throughout to help get a picture of the bones that help paleontologists understand what these ancient oceans and their inhabitants were like.
Profile Image for Lila.
73 reviews
August 8, 2022
I've really enjoyed picking this book up occasionally over the years and learning a little bit more each time about the Western Interior Sea of Kansas so long ago. Ever since I learned as a teenager that the Kansas Statehouse in Topeka is made of local limestone from an ocean that was once right here in our state, I was fascinated. Dr. Everhart carefully pieces together in this work what life was like in the ancient seaway, as well as a comprehensive history of the paleontological discoveries in our state. 🌾🌊 If you're interested in geology or paleontology of Kansas this is the book!

I was excited to see the author speak at my local library this summer as well!
471 reviews3 followers
March 14, 2023
About 85 million years ago, there was a vast shallow inland sea ranging from the Gulf of Mexico to the Arctic Ocean and Hudson Bay. Monstrous creatures lived in this ocean, died, were covered in chalky detritus and were eventually discovered as Western Kansas became settled by farmers. The author is a paleontologist who specialized in Kansas fossils. There are large collections in museums in Hays, Lawrence, Oakley, and Wallace Kansas, including the most published fossil photo, the fish within a fish of the Sternberg Museum. This book is filled with heavy technical details and many, many Latinized species names, but the author also includes many personal details of how he, his students, his wife and son, and even amateur high school students discovered many important finds.
89 reviews1 follower
February 19, 2024
Extremely organized and detailed

I really appreciated the amount of data and the history of the discoveries. I was less enthusiastic about the constant barrage of scientific names of the organisms, without some illustrations of the creatures. So many bones & so few illustrations of the live forms! Apparently, even with a degree in geology and burning curiousity, this text was too laboratory intensive to truly enjoy.
Profile Image for Zhelana.
895 reviews2 followers
November 17, 2023
This book was good for having a little imaginative snippet about how a species of each type of animal discussed lived and died, and showing them all interacting. However, then it got into long technical descriptions that mostly read like "a large body with a long snake like neck and fins" and I really didn't know what differentiated some of the different categories of animals we talked about. We also talked a lot about sharks and fish, and I wasn't entirely sure how these were any different than those we have today. But then there were the descriptions of Everhart doing his work and taking his friends out to hunt fossils and those sections were pretty fun. Overall it was alright, but I wouldn't really recommend this book unless you're already a particular fan of life in the past. I think I said that the last time I read a book in this series, too. But I don't think I'll read another. It was interesting enough I guess, but not a great book, and that's exactly what I said about the other book. It does have the advantage of being accessible and written for a popular audience, though, which I guess isn't found much amongst scientists who study animals that lived with the dinosaurs that were not dinosaurs. So maybe it's worth reading if you're curious about that specific subtopic.
Profile Image for Kyle.
419 reviews
June 28, 2025
Excellent history of the fauna of the Western Interior Sea during the Cretaceous. I enjoyed the short vignettes at the start of each chapter describing potential animal behavior. The book can be quite technical at times, however, so a casual reader may not enjoy this volume as much. That being said, the details are usually interesting and there is a lot of paleontologist rivalry from Cope and Marsh that injects some fun stories into the mix.
Profile Image for Mallory Kellogg.
Author 2 books29 followers
Read
August 3, 2020
Way too technical for me. This would be great for a geology fan, but I'm more about dinosaur behavior and environment. Not about Chalks and mud deposits. That's just my personal feelings, and this book is actually very packed with information. Just not something I can follow, understand and gain anything from.
16 reviews
July 17, 2022
Very extensive and informative writing on the specific topic of the western interior seaway, dry and academic but thats part of the fun. only wish more time was spent of the actual lives and ecology of the animals discussed and maybe not so much on the paleontologists that have worked on the area, important as their contributions to science are...
Profile Image for Phil.
2,040 reviews23 followers
January 14, 2022
Great read. A bit dry because of the textbook style descriptions but I learned a lot and only had to look up four or five new words. And if I ever visit the Midwest, I know where to stop to fossil hunt.
Profile Image for Beige Alert.
271 reviews4 followers
November 15, 2025
Felt much of the time like more of a history of amateur hobbyists and professional Paleontologists.

Five stars if I gave a damn about them and their intratribal associations and conflicts rather than the subject of the title.
Profile Image for Donna.
35 reviews
July 31, 2019
Very technical but a great read if you are a science nerd.
Profile Image for Judi.
794 reviews
July 30, 2022
Fascinating to see what history is buried in the layers of Kansas.
90 reviews
April 10, 2023
Loads of info which I love. A trifle dry at times. All in all good read.
5 reviews
April 16, 2023
Great book! Full of interesting paleo history. A must-read for people in the area interested in the natural wonders of Kansas.
105 reviews
December 21, 2024
I would not call this an "entertaining" read but it's chock full of good scientific information if you need to do a research paper.
Profile Image for Nicole Geub.
977 reviews1 follower
March 27, 2025
I don't like that this was written in pure -ologist jargon. I was bored trying to listen to unpronounceable words and scientific names of fish and dinosaur species. Kinda disappointing.
Profile Image for Robert Clark.
Author 16 books26 followers
June 30, 2024
An excellent account of the evolution and balance of life in the inland sea once covering much of North America.
186 reviews2 followers
March 19, 2023
This book relates the history of the Western Interior Sea, Ocean of Kansas. It is a compilation of the life's work of the author. I particularly enjoyed learning about the early paleontology work done by Liedy, Cope, and Marsh in the Smoky Hill Chalk and Pierre shale. The author is definitely an expert in Plesiosaurs, pliosaurs, mosasaurs, and pterosaurs found in Kansas and his enthusiasm is infectious. The Lewis and Clark expedition was expected to find some large animals on their trip, since Thomas Jefferson had found mammoth/mastodon bones in Kentucky, perhaps they existed farther west. In fact, Lewis and Clark did find a fossil of S. lanciformis a long eel-like fish with a sword-like beak on its lower jaw. Also, expedition journal notes recount their finding a 45 foot long "fish" that was possibly a mosauarus.
Profile Image for Heather Turiello.
422 reviews33 followers
March 19, 2023
I was excited to read this after living in the state for 30 years, but honestly was a little disappointed. To be fair, it felt like this book was written more as a diary or personal documentation about his career and excitement about the discoveries. But the tone doesn't feel like a book written for the general citizen wanting to hear more about prehistoric wildlife. There was this documentation about the discoveries and a bit about what the central ocean was like, but there was also a lot about the conferences he attended worldwide to discuss findings. I wish a good editor would go through it and clip out the parts that are generally not interesting about meetings and conferences and focus on what he learned and what he'd like to educate residents on about their state.
1 review
August 15, 2018
This book is AWESOME! This is the important book on this subject and is very informative. Very few books ignite my imagination more. Lay readers may have a harder time with it because it get kinda technical, or at least technical to some standards however it is a fascinating read. I highly recommend getting the 2nd edition. It is worth the read and it has better figures.
Profile Image for Jimmy.
770 reviews22 followers
September 28, 2024
Pretty good book on the various fossils discovered in Kansas; it also covered some of the history of paleontology in the state. However, it is also riddled with evolutionary garbage all through the book.
Profile Image for Jerry.
16 reviews
April 1, 2010
Cretaceous life in the Oceans, Difference between elasmosaur and short-necked plesiosaurs.
34 reviews2 followers
August 2, 2010
had a hard time with this one. Didn't really get into it.
Profile Image for Josh.
499 reviews4 followers
September 25, 2014
Poorly written, and with nary a trace of entertainment value. It's detailed enough to be of use were one to frequently hit the chalks of Kansas, but otherwise this book is awful.
Displaying 1 - 30 of 32 reviews

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