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Xiphactinus audax Leidy 1870

(...not Portheus molossus Cope 1872)

Largest Bony Fish of the Late Cretaceous Seas

Copyright © 2000-2013 by Mike Everhart - Last revised 08/01/2013






LEFT: This Xiphactinus audax shown in mid-jump in a painting by D.W. Miller... Note that the jaws of the fish are about 8-10 feet above the surface of the water.  That's BIG!! © D. W. Miller, used with  permission.

Recently I came across a figures in Mantell's 1822 work, The Fossils of South Downs (LEFT) and a Mantell's 1833 Geology of the South-East of England (RIGHT- reversed) that undoubtedly represents a specimen of a small Xiphactinus. The total length of the jaw is given as about 5 inches. In the second book, he regarded the jaw as belonging to an unknown reptile (See description below). A recent check with the British Museum of Natural History indicates that the specimen is still there and is curated as BMNH (OR)4066. 

Note that this specimen was fully reported by O.P. Hay in 1898: "The earliest reference which we have to any remains of the genus of fishes usually called Portheus is that found in Mantell's Geology of Sussex, p. 241, P1. XLII, 1822. No systematic name is there assigned to this fish. Later, Louis Agassiz, in his Poissons Fossiles, vol. v, p. 99, referred to Mantell's description, and refigured the materials (op. cit., PI. XXV b, Figs. I a, I 6),presenting at the same time additional figures of remains from the same locality (Pl. XXV a, Fig. 3; P1. XXV b, Figs. 2, 3). All these he included, with other remains, under the name Hypsodon lewesiensis."

From Mantell, 1833, p. 152-153: 

"Undetermined Reptiles. - A lower jaw, with twelve smooth, pointed, slightly convex teeth, was figured in the Fossils of the South Downs , as the jaw of a fish. There can scarcely admit of a doubt that it belongs to a saurian animal: a figure is annexed. The original is five inches long; the fangs of the anterior teeth, like those of the crocodile, are hollow, fixed in sockets, and not attached to the jaw; but their smooth polished surface, and flattened form, separate them most decidedly from the animals of that family. The posterior teeth are affixed to the edge of the jaw, a mode of dentature observable in many kinds of fishes. The structure of a vertebra found with the jaw is decidedly that of a fish, the conical cavities being very deep; and it possesses the annular markings so constantly observable in the vertebrae of fishes. A cylindrical bone was also found, but was too much injured to allow of any correct inference being drawn from it. The posterior extremities of a lower jaw of a reptile were found in the same block of chalk, with portions of the upper and lower maxillae bearing many teeth, and corresponding with those of the last mentioned fossil; and fragments of other maxillae have since been discovered: the materials at present in my possession are, however, too imperfect to admit of the zoological relations of these remains being accurately determined."

So after identifying the specimen as the lower jaw of a fish in 1822, Mantell changed his mind and decided it was actually the jaw of an unidentified reptile in 1833.

LEFT: But the story doesn't end there.. Louis Agassiz in Volume 5 of his "Recherches sur les Poissons Fossiles" (1833-1845) published yet another drawing of the specimen on Plate 25b, correctly regarded it as the jaw of a fish, and gave it a name - "Hypsodon lewesiensis." (see page 99).

Newton (1877) revisited this specimen and others, and correctly identified the specimen as "Portheus" then based on the number of teeth in the premaxilla (5), gave it a new species name, Mantelli, close to Cope's "P. lestrio" and "P. Mudgeii"  (see page 510).

The story was recounted again by O.P. Hay (1898) in his paper noting that Xiphactinus Leidy was the senior synonym of Portheus Cope (Observations on the genus of fossil fishes called by Professor Cope, Portheus, by Dr. Leidy, Xiphactinus).

Bardack (1965) was the next to discuss the specimen in his "Anatomy and evolution of Chirocentrid fishes." According to Bardack (p. 37), Agassiz had originally named the specimen Megalodon in 1835, but upon finding the genus name preoccupied, changed it to Hypsodon in 1837. He also notes that  the first Hypsodon species named by Agassiz is a pachyrhizodid, not an ichthyodectid, so Leidy's genus is valid and has priority. 

LEFT: The partial skull of an Early Cretaceous (Middle Albian) Xiphactinus audax from southeastern England figured by Newton (1877, p. 512, plate XXII, fig. 1):

Portheus gaultinus, n. sp. PI. XXII. figs. 1-12.

Mrs. Elizabeth Warne has recently enriched the Museum of Practical Geology by the presentation of a very fine specimen of Portheus, which was obtained through Mr. E. Charlesworth, from the Gault of Folkestone. This specimen includes the greater part of upper and lower jaws of both sides, with a considerable portion of the brain-case and bones of the ethmoidal region, also several vertebrae and fragments of bones which cannot be identified. The generic relationship of this specimen to the American Portheus cannot be doubted;  specifically it is so closely allied to P. lestrio, Cope, that one might at first be inclined to refer it to that species; but, besides its much smaller size, it exhibits certain peculiarities which prevent its being regarded as the same. Each of the parts will now be considered separately.

Back to the Western Interior Sea....

After his 1871 trip to Kansas, E.D. Cope (1872a) was reported to have said, "At a similar location on Fox Creek, M. V. Hartwell found the skeleton of a very large fish, with "uncommonly powerful offensive dentition," probably of the Saurodonts. He [Cope] names this Cretaceous species Portheus molossus.

In a later report Cope (1872b) wrote, "The head was as long or longer than that of a fully grown grizzly bear, and the jaws were deeper in proportion to their length. The muzzle was shorter and deeper than that of a bull-dog. The teeth were all sharp cylindric fangs, smooth and glistening, and of irregular size. At certain distance in each jaw they projected three inches above the gum, and were sunk one inch into the jaw margin, being thus as long as the fangs of a tiger, but more slender. Two such fangs crossed each other on each side of the middle of the front. This fish is known as Portheus molossus, Cope [a junior synonym of Xiphactinus audax Leidy 1870]. Besides the smaller fishes, the reptiles no doubt supplied the demands of his appetite."

xfish-t1.jpg (55231 bytes) LEFT: One of the largest Xiphactinus audax known (17 feet long) - Early Santonian age, Smoky Hill Chalk Formation, Gove County, KS. Discovered by Mike Everhart, 1996. Collected,  prepared and displayed by Triebold Paleontology.

Here's another 17 footer discovered and collected by a friend of mine... with his three kids thrown in for scale...

"The Portheus, now swimming for life, was the foci of the sharks that were coming to the attack from all directions. One would dive under the fish, and receive, for his pains, a stroke from his powerful tail that would put him out of commission; another would receive a thrust from the sword-like ray of the front fin. Undaunted, others hurried up like a pack of wolves on a wounded deer. Though many were wounded in the fray, our hero fish at last succumbed to numbers, who gashed his body with their lance-like teeth, and the water was tinged with his life blood, until, weakened and overpowered, he gradually ceased struggling. The sharks gathered to the feast. One, however, was so badly wounded by the Portheus, that he went to the oozy bottom with him. I have preserved in the Museum of the University of Kansas a shark twenty-five feet long, and mingled with his remains were the bones of a Portheus, the evident result of such a combat … “

Excerpted from Charles H. Sternberg's "Hunting Dinosaurs on the Red Deer River, Alberta, Canada" (1917, p. 162).  While the passage from C H. Sternberg's book is fiction, it is based on the discovery of the remains (KUVP 247) of a large Cretoxyrhina mantelli (Ginsu shark) that also contains the scattered bones of a large Xiphactinus as its last meal. The specimen is on exhibit in the University of Kansas Museum of Natural History in Lawrence, Kansas (below) 

xiphmeaa.jpg (4234 bytes) LEFT: Sometimes, the tables were turned and the hunter became the meal.  This is photograph of a disarticulated shark specimen (KUVP 247) at the University of Kansas Museum of Natural History.  The most interesting thing about the find was the remains of a large Xiphactinus audax inside the shark when it died. Note the large lower jaw, with teeth, in the upper center of this picture. Xiphactinus ribs are also scattered among the shark vertebrae.  The skull of the shark (Cretoxyrhina mantelli)  was preserved with dozens of teeth still in place in the jaws. (Found by George Sternberg, 1908 and described by Charles H. Sternberg in 1917 (see above note).

RIGHT: The left maxilla of a shark scavenged Xiphactinus (KUVP 12011) with some of the many Cretoxyrhina mantelli teeth that were discovered in association with the remains. 

prentica.jpg (26101 bytes) Xiphactinus audax, [Zy-fac-tin-us] or as it is more commonly called, the "Bulldog Fish", was a species of very large predatory fish that lived in the ocean during the Late Cretaceous.

LEFT: A detailed drawing by Prentice of the skull of Xiphactinus from volume 6 of the University Geological Survey of Kansas (Stewart, 1900).  LARGE FILE

RIGHT: The articulated skull of a large Xiphactinus audax in our collection in right lateral view (scale = 10 cm). This specimen was found by my wife in 1989 in Gove County. The skull was prepared out by Katie Conkling in 2007, including the discovery of two Squalicorax falcatus teeth lying on the sagittal crest. (A view of partially prepared left side of the skull is HERE)   The "Evil Eye" was added by her son, Mike....

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leidy-65.jpg (16287 bytes) RELATED HISTORICAL NOTE:

Leidy (1856) gave a short description of a single tooth found in the Cretaceous marl of New Jersey and named it Polygonodon vetus:

"Based on a specimen of the crown of a tooth found in the marl (cretaceous) of Burlington County by L. T. Germain, Esq.,   Length three times the breadth; transverse section elliptical; with trenchant borders; with six planes on one side and seven on the other. Length 1½ inches, breadth ½ an inch. May be an incisor of Mososaurus [sic]?"

Leidy (1865) described the tooth in greater detail and included three figures (left) showing what it looked like in (12) posterior, (13) external view, and in cross section. Still believing the tooth to be reptilian, he thought it "may have belonged to Discosaurus or Cimoliasaurus, but the matter must be left for future determination."

The tooth was later determined to be from a sister species of Xiphactinus audax, raising the issue of which genus name should have priority... Polygonodon Leidy 1856 or Xiphactinus Leidy 1870? 

See Schwimmer, et al. (1997) for a more detailed explanation. Most likely it will remain Xiphactinus.

garret1a.jpg (38548 bytes) Although they were not closely related, a Xiphactinus would have looked much like a modern Tarpon. The fish probably attained lengths of 18 to 20 feet, and some 'giant vertebrae' from marine deposits in Arkansas indicate that some individuals that were even larger. Xiphactinus audax painting and skeleton woodcut © Ron Garrett, used with permission of Ron Garrett garret2a.jpg (49163 bytes)
leidyp17a.jpg (53917 bytes) While the name Xiphactinus has been around since 1870, there has been considerable confusion over which name is actually correct? : Xiphactinus audax (Leidy, 1870) or Portheus molossus (Cope, 1872)

LEFT: In 1870, Joseph Leidy named the fish from a 16 inch (40.6 cm) long fragment of a pectoral fin ray (USNM V52), collected by Dr. George M. Sternberg, more than a year before E. D. Cope gave the name of Portheus molossus to a collection of several nearly complete specimens found near Fort Wallace.  Leidy's name is correct by virtue of being the first to be published, but Cope's name was more popular and is still in use (incorrectly) in many collections of Cretaceous fish.

USNM V52-1a.jpg (27961 bytes) LEFT: A 2009 photo of the USNM V52 Xiphactinus audax type specimen in ventral view. Photograph by Susan Liebl (Copyright © Susan Liebl, used with her permission, and courtesy of the Smithsonian Institution, United States National Museum, Washington, D.C).
LEFT: The right pectoral fin (dorsal view) of Xiphactinus audax from Osborn (1904). The specimen (above) collected by Dr. Sternberg and used as the type species of Xiphactinus by Leidy would have been the largest fin ray at the top of the figure. 

Note here that prominent paleontologists like Osborn were largely responsible for continuing the usage of the junior synonym (Portheus molossus) even though it had been corrected earlier by O.P. Hay (1898), and A. Stewart (1898). 

LEFT: The fossilized remains of these fish, especially skull fragments and vertebrae, are fairly common in the Smoky Hill Chalk. Sometimes, the skeletons are very complete, such as this famous fossil of a "fish-within-a-fish" excavated by George F. Sternberg in 1952 (George is on the far left in the picture). This specimen is about 13 feet long and is on permanent display in the Sternberg Museum in Hays, Kansas. The six foot long, 'last' meal' is a related species of ichthyodectid fish called Gillicus arcuatus

George F. Sternberg was the nephew of the Dr. George M. Sternberg who sent the original Xiphactinus type specimen from Kansas to Dr. Joseph Leidy sometime before 1870.

LEFT: The famous "fish-within-a-fish" Xiphactinus audax specimen (FHSM VP-333) at the Sternberg Museum of Natural History (Click picture to see much larger version (190 kb). The stomach contents (a large Gillicus arcuatus) is curated as FHSM VP-334. The Xiphactinus is just over 13  feet long.

Contact me for a copy (.pdf file) of Myrl V. Walker's account of the discovery and recovery of this famous specimen: "The Impossible Fossil." It's an interesting historical account and a great description of the "Sternberg method."

LEFT: "Xiphactinus on the Prowl" by Dan Varner. We do not know if Xiphactinus was solitary or swam /hunted in schools, but there were lots of them in the Western Interior Sea.

RIGHT: The final moments in the life of the "Fish-within-a-Fish"... A 13 foot Xiphactinus that swallowed a 6 foot long Gillicus... and then died suddenly.

LEFT: Another specimen of Xiphactinus audax (originally AMNH 32219; new number is AMNH FF 13102) collected in 1901 by C.H. and G. F. Sternberg, and sold to the American Museum of Natural History. (15 feet, 8 inches long; see Osborn 1904, Figure 1). 

Note here that prominent paleontologists like Osborn were largely responsible for continuing the usage of the junior synonym (Portheus molossus) even though it had been corrected earlier by O.P. Hay (1898), and A. Stewart (1898). 


xiphyala.jpg (21240 bytes) LEFT: Still another G. F. Sternberg specimen of Xiphactinus audax. This one is in the Yale Peabody Museum collection. See Thorpe (1934).
UNSM X-Fisha.jpg (28124 bytes) LEFT: This is the Xiphactinus audax specimen (3.5 m) originally displayed in the museum at the Kansas State Teachers College (now Fort Hays State University). It was collected by G.F. Sternberg in 1926 on the south side of Twin Butte Creek in Logan County. This specimen was sold to the University of Nebraska State Museum in 1952 and then replaced with the current, much more famous "fish-within-a-fish" exhibit.

RIGHT: A recent picture of this same  specimen (University of Nebraska State Museum: UNSM 1495). Note that it also contains the remains of a last meal... another Gillicus.

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gfs-02a.jpg (18195 bytes) LEFT: Two views in the field of another Sternberg Xiphactinus collected near Monument Rocks in Gove County  - From the archives of the Fick Fossil and History Museum, Oakley, Kansas.

RIGHT: The "business end" of 15 foot long Xiphactinus audax collected and prepared by G. F. Sternberg in 1946 from Gove County, KS. You can see the caudal fin of a 7 foot long Gillicus just behind the gills of the Xiphactinus. Although the smaller fish is partially digested, the death of the larger fish probably occurred within hours of this last meal. The specimen (DMNH 1667) is currently on exhibit in the Denver Museum of Science and Nature.   (See Rogers, 1991, p. 244-246)

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Charles H. Sternberg (1922) reported that he had found a remarkable skeleton of "Portheus." He noted that "it was preserved from the pelvic fins to the end of the tail, and is the largest Portheus I have seen. The spread of the tail fins is five feet. In 1918, my son Levi found a skull and body part of a Portheus that is so near in size to this one that I have made a composite skeleton of the two. It is sixteen feet long and will be, as I said, the largest bony fish ever collected from the Cretaceous."
LEFT: Xiphactinus as the last meal of a large shark - KUVP 247 in the University of Kansas Museum of Natural History.

George F. Sternberg discovered  the remains of a large Cretoxyrhina mantelli (Ginsu shark) in Trego County that contained the scattered bones of a large Xiphactinus as its last meal. The specimen was sold to the University of Kansas Museum of Natural History in Lawrence, Kansas where it is currently on display..

Larger view of the Cretoxyrhina jaws and teeth.     Larger view of the exhibit

Larger view of the Xiphactinus remains found inside the shark

The Fick Fossil and History Museum at Oakley Kansas has a large Xiphactinus audax specimen that was found and prepared by G. F. Sternberg in 1926. It was originally purchased by the town of Oakley for their public schools (Rogers, 1991). This specimen is about 13.5 ft long.  The fish is so large that I had to take four photographs to get all of it into this composite photograph.
OakleyX-fish3a.jpg (23165 bytes) LEFT; G. F. Sternberg puts some final touches on the Xiphactinus audax specimen he prepared for the Oakley School system. (Photo in the G.F. Sternberg archives, Forsyth Library, Fort Hays State University)
OakleyX-fish2a.jpg (8129 bytes) LEFT: G. F. Sternberg (at right, white lab coat) talks about this specimen with students of the Oakley Public Schools about 1926 when it was acquired by the the school for exhibit.   (Photo in the G.F. Sternberg archives, Forsyth Library, Fort Hays State University)
fickxipa.jpg (14370 bytes) LEFT: Click the thumbnail for a better view of the business end of the above specimen of Xiphactinus audax. The largest teeth are in the upper jaw in two paired bones called 'premaxillae'. They are about three inches long and are conical in shape for seizing prey.  When the single large tooth was ready to be replaced, there were two smaller teeth, growing one on reach side to take over.

Unlike many large sharks of the period, Xiphactinus was not capable of biting pieces off its prey and instead, swallowed them whole. This tended to get them in trouble, particularly when the prey was large and struggling. A number of specimens have been found with large,  partially digested fish still inside (most frequently Gillicus arcuatus, suggesting that the larger fish died while or immediately after swallowing its prey.

fickno3a.jpg (15225 bytes) LEFT: The skull of another Xiphactinus audax in the Fick Fossil and History Museum, Oakley, Kansas.  Recently I found G. F. Sternberg's field notes regarding the discovery, preparation, and disposition of this specimen:
"Oct. 28th, 1924 - Sp. 3 – Portheus molossus of Cope       Locality - 3/4 mile south of the locality of no. 2
Horizon – Cretaceous chalk                                                 Collector – G. F. Sternberg
Description – Skull quite complete except for a small portion of the back part of the gills. The left side of the skull is exposed and it is an individual which would be about 12 feet long. The bones are well preserved. Plaster is run in so as to appear the bottom side. One section - size 32” x 35” x5” [Hand drawn picture here] As seen in quarry of opposite side.
School collection no-1- includes this skull which when opened on right side proved to be very fine.

LEFT: The exhibit specimen of Xiphactinus audax in the Hastings Museum, Hastings, Nebraska. Collected by G.F. Sternberg from the Smoky Hill Chalk in southwestern Trego County, Kansas.

RIGHT: Another X. audax specimen in the collection of the University of Nebraska State Museum.  This one was collected by G.F. Sternberg in 1931. 

FHSM VP-2973Aa.jpg (17267 bytes) LEFT: The "exploded" skull of a relatively small Xiphactinus (FHSM VP-2973) from the Smoky Hill Chalk collected by Marion and Orville Bonner in 1959. This fish would have been only about 8 feet long when it died. Fish skulls often come apart (explode) like this during decomposition.

RIGHT: The very impressive lower right dentary (medial view) and right premaxilla of the same specimen. 

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VP16640-3a.jpg (23474 bytes) LEFT: Unusual preservation of a Xiphactinus audax skull (FHSM VP-16440) in left lateral view. The specimen was collected in 2005 from the upper chalk of western Gove County. The lower jaw is smashed backwards to the point that it is nearly perpendicular to the vertebral column. This would suggest a high speed, head-first impact with a sea bottom that was NOT soft mud. 

RIGHT: The same specimen looking head on. Note that the large teeth in the lower jaws are pushed up between the premaxillae and that the "facial" region of the skull, including the orbit of the left eye has been crushed inward.  HERE IS a close-up of the front of the jaws.

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vp-9256w.jpg (20651 bytes) LEFT: An upside down view of a large Xiphactinus audax (FHSM VP-9256) skull in the Sternberg collection. The skull must have landed upright on the sea bottom and was buried and later preserved that way. The large tooth at the right is about 2 inches long.

RIGHT: Close-up of the same skull showing the left maxilla laying outside the left dentary. The small bones  (hyoids) between the lower jaws support the gills.

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vp-9256z.jpg (22429 bytes) LEFT: A close-up of the scapulo-coracoid bone of FHSM VP- 9256) showing where the pectoral fins are attached. The specimen was collected by T. E. Herman in 1987 from Ellis County.

RIGHT: The photo shows the extent of the bony pectoral fins of Xiphactinus. The fin ray on the fin in the left side of the picture is 55 cm (22 in.) long.  Note that most of the leading edge of the fin is actually composed of a much shorter fin ray.

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LEFT: The pectoral (shoulder) girdle of Xiphactinus audax, shown in caudal (rear) view, adapted from McClung 1908 (Plate X).

RIGHT: A similar girdle in my collection showing a cross-sectional view of body of the fish at the shoulders and the relationship of the vertebral column and the pectoral fins.

x-vert1a.jpg (18137 bytes) LEFT and RIGHT: Two views of the vertebrae of Xiphactinus audax. Large vertebrae like these are fairly common finds in the chalk. These specimens are medium in size for Xiphactinus, about 5 cm (2 in.) in diameter and 3 cm. long, and probably came from a fish that was about 3 m (12 ft) in length. According to Bardack (1965), Xiphactinus had an average of 85 vertebra. x-vert2a.jpg (22509 bytes)
XiphactinusSite0a.jpg (23287 bytes) LEFT: In October, 2009, I chanced upon the remains of a Xiphactinus in a road cut near Wilson Lake in Russell County, Kansas. The specimen had originally been located by a friend of mine (Keith Ewell) about 5 years ago, so I cannot claim full credit for the discovery, but I had never known the exact location. The ledge above my head is the Fencepost Limestone, used long ago for building stone and to make stone posts like the one on the crest. There were very few trees in the western part of Kansas at the time it was settled (1870s-1890s). A dining room table-sized chunk of this layer had fallen off and was standing vertically in the ditch to my right. I wasn't very eager about tunneling in too far. Here I am using a hammer and chisel to remove chalky layers of the Pfeifer Shale from above and below the fish vertebrae that were coming straight out of the hillside. While the shale was fairly soft and easy to work, it was difficult to remove because I kept sliding down the slope. (Dig pictures by Lee Garrison).

RIGHT: These are the 3 vertebrae that I recovered from the dig. The one that I discovered initially is on the left of the photo. The one at the right was still articulated with at least one more vertebra. The remains come from a medium sized Xiphactinus... probably 12-14 feet in length. Although Xiphactinus is known to occur somewhat earlier than this discovery, this is the first specimen from the Pfeifer Shale Member of the Greenhorn Formation.

PfeiferX-Fish1a.jpg (14566 bytes)
xshark8a.jpg (3027 bytes) xshark6a.jpg (3375 bytes) xshark9a.jpg (3884 bytes) xshark3a.jpg (3788 bytes) This Xiphactinus audax (ESU 1047) skull is on exhibit at the Geology Museum at Emporia State University, Emporia, Kansas. It had been bitten by a large Ginsu (Cretoxyrhina) shark which left a calling card in the form for a broken tooth wedged in the third vertebrae behind the skull. (See Shimada and Everhart, 2004)
bmnsxipa.jpg (7100 bytes) LEFT: This is a picture of a large Xiphactinus (BMNH P. 11125) in the British Museum of Natural History. The specimen was found by George Sternberg and sold to the museum by Charles Sternberg. The picture was taken by the parents of Charles Choguill,  when they were in London in 1959-1960. According to Mr. Choguill, this specimen and other Kansas fossils were no longer on exhibit when he visited the BMNH in 1971. More recently (10/2007), Matt Friedman indicated that it was currently on display in the Earth Gallery (the old Museum of Geology).

RIGHT:, George Sternberg uncovers the skull of another Xiphactinus (Photo provided by Charles Choguill).    

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The following is a note written in regard to the above specimen (Sternberg, 1917, p. 11-12) and includes Charles Sternberg's annotations of a story in the London Illustrated News:

"In 1911, I sent George to western Kansas with a party to collect in the Chalk, and with wonderful results; for though I had secured four skeletons of the famous Tarpon-like fish of the Cretaceous, named Portheus molossus by Cope, he succeeded in finding the most complete skeleton known to science, now mounted in the British Museum of Natural History, in London. Mr. Pycraft has pictured it in the London Illustrated News for March 1, 1913. "The giant to which I refer now" (he says) , "has been dead a very long while, a million years or so [over 5,000,000 - C. H. S.]. Its remains in a most extraordinary state of preservation, will be found in the Geological Gallery. Measuring just fourteen feet in length, it must have weighed between four and five hundred pounds [a thousand likely. - C. H. S.]. It was obtained from the chalk of Kansas, and has quite a remarkable history. It was found by Professor Sternberg, who has achieved a world-wide fame for his discovery of fossil fish and his quite amazing skill in digging his finds from the rock in which they are embedded. The specimen was found [by George F. Sternberg], exposed at the surface of the ground, and was much the worse for wear and tear of wind and rain and sun. But Professor Sternberg was equal to the occasion. For just as there are two sides to every question, so there are two sides to every fossil. The resourceful discoverer determined to get at the other side of this very stale fish; for the exposed side was useless. Accordingly he covered it with a thick layer of plaster of Paris and when this was set he proceeded to dig out the fossil from the bed of chalk. This accomplished, he cut away the rock from the specimen, and eventually succeeded in exposing the whole fish." [The underside at least.- C. H. S.]"

The specimen is described by Woodward 1913 -  Click here for Woodward's Plate XXIII.

Click here to see pictures of a dig done by Triebold Paleontology on a very large (17 ft - 5.2 m) Xiphactinus that I found in in 1996 in Gove County, KS.  This specimen is on exhibit in the North American Museum of Ancient Life in Lehi, Utah and elsewhere with  the traveling "Savage Ancient Seas©" exhibit. In September, 2003, I examined a beautiful, completely articulated specimen that had been found by a private collector in Trego County.  It would have been 17 feet long but was missing the front part of the skull.

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This specimen shown above is certainly the largest example of this species ever mounted and may the the largest complete specimen ever found.  In her book on the Sternberg fossil hunters, Rogers (1991, p. 250) mentions that George Sternberg had found specimens as long as seventeen feet (5.1 m), but they were not complete. The remains also included stomach contents consisting of a partially digested Gillicus.
XIPHJUVA.jpg (10693 bytes) Although we know that Xiphactinus grew to be very large as adults, we know very little about them as juveniles. So far as I am aware, there are no juvenile specimens of this species in the Sternberg, or University of Kansas collections. At LEFT and RIGHT are two views of a very small specimen of Xiphactinus audax that I collected in 1999. It still needs to be prepared, but consists of one premaxilla and both of the dentarys which are preserved together. When alive, this fish would have only been about 30 cm (12 in) long.  The single tooth in the premaxilla measures 8 mm, compared with 65+ mm in a large adult.  Until these little guys grew up, they were food for everything larger than they were...  very few made it. XIPHJUVB.jpg (13580 bytes)
bonner1a.jpg (9823 bytes) This nearly complete Xiphactinus specimen was discovered and prepared by Chuck Bonner.  It is on exhibit in the Keystone Gallery, 25 miles south of Oakley in Logan County, Kansas. This fish must have bloated after death and then was contorted into this unusual shape.

Click here for Gary Staab's wonderful paleo-art on YouTube--- Creating a 3-D Xiphactinus sculpture for the Hastings Museum, Hastings Nebraska.

Click here to see pictures of the 3-D mount of a large Xiphactinus audax in the Sam Noble Oklahoma Museum of Natural History at the University of Oklahoma.

Click here for a webpage about the discovery of a much earlier Xiphactinus (Cenomanian-Turonian) in Iowa.

LEFT: Head on view of the lower jaws between the premaxillae of the first Xiphactinus audax reported from South America (Venezuela).

RIGHT: Vertebrae of the same specimen. (Photos courtesy of Jorge Carrillo-Briceño)

See: Carrillo-Briceño, J., Alvarado-Ortega, J. and Torres, C. 2012. Primer regristro de Xiphactinus Leidy, 1870 (Teleostei, Ichthyodectiformes) en el Cretácico de América del Sur (Formación La Luna, Venezuela). Revista Brazileira de Paleontologia 15(3):327-335.


Other Oceans of Kansas webpages on Late Cretaceous fish:


Field Guide to Sharks and Bony Fish of the Smoky Hill Chalk



Kansas Shark Teeth

Cretoxyrhina and Squalicorax




Bony Fish


Pycnodonts and Hadrodus












Saurodon and Saurocephalus


Suggested References:

Agassiz, J.L.R. 1833-1845. Recherches sur les Poissons Fossiles. Neuchàtel and Soleure, Volume V, i-xii, 1-460l; Vol. V Atlas, Plates A-M, 1-64.  

Bardack, D. 1965. Anatomy and evolution of Chirocentrid fishes. University of Kansas Paleontological Contributions, Article 10, 88 pp. 2 pl.

Carrillo-Briceño, J., Alvarado-Ortega, J. and Torres, C. 2012. Primer regristro de Xiphactinus Leidy, 1870 (Teleostei, Ichthyodectiformes) en el Cretácico de América del Sur (Formación La Luna, Venezuela). Revista Brazileira de Paleontologia 15(3):327-335.

Cope, E.D. 1871. On the fossil reptiles and fishes of the Cretaceous rocks of Kansas. Art. 6, pp. 385-424 (no figs.) of Pt. 4, Special Reports, 4th Ann. Rpt., U.S. Geol. Surv. Terr. (Hayden), 511 p. (Cope describes and names Portheus molossus)

Cope, E.D. 1872a. On Kansas vertebrate fossils. American Journal of Science, Series 3, 3(13):65.

Cope, E.D. 1872b. On the geology and paleontology of the Cretaceous strata of Kansas. Preliminary Report of the United States Geological Survey of Montana and Portions of the Adjacent Territories, Part III - Paleontology, pp. 318-349.

Cope, E.D. 1872c. [Sketch of an expedition in the valley of the Smoky Hill River in Kansas]. Proc. Amer. Phil. Soc. 12(87):174-176.

Cope, E.D. 1872d. On the families of fishes of the Cretaceous formation in Kansas. Proceedings of the American Philosophical Society 12(88):327-357.

Hay, O.P. 1898. Observations on the genus of fossil fishes called by Professor Cope, Portheus, by Dr. Leidy, Xiphactinus. Zoological Bulletin 2(1): 25-54.

Hay, O.P. 1898. Observations on the genus of Cretaceous fishes called by Professor Cope Portheus. Science, 7(175):646.

Hay was quoted: "Professor O.P. Hay made some 'Observations on the genus of Cretaceous Fishes, called by Professor Cope Portheus' discussing the osteology of the genus at some length and particularly the skull, shoulder girdle and vertebral column. He said that in many respects it resembled the Tarpon of our Southern coasts, although possessing widely different teeth, and undoubtedly belonged to the Isospondyli. The conclusion reached that Cope's Portheus is identical with the earlier described genus Xiphactinus of Leidy. (Since the paper was read, the author has learned that Professor Williston has reached the same conclusion.)"

Leidy, J. 1856. Notices on remains of extinct vertebrated animals of New Jersey, collected by Prof. Cook of the State Geological Survey under the Direction of Dr. W. Kitchell. Proceedings of the Academy of Natural Sciences of Philadelphia, 8:221. (printed in 1857 - Naming of Polygonodon vetus, a sister species of Xiphactinus audax, and Ischyrhiza mira Leidy)

Leidy, J. 1865. Cretaceous reptiles of the United States. Smithsonian Contributions to Knowledge 14(6):1-135, pls. I-XX. (Three figures and a more detailed description of the tooth of Polygonodon (Xiphactinus) vetus Leidy 1856) <EM>

Leidy, J. 1870. [Remarks on ichthyodorulites and on certain fossil Mammalia.]. Proc. Acad. Nat. Sci. Phil. 22:12-13. (The naming of Xiphactinus audax from a fragment of a pectoral fin found by Dr. George M. Sternberg (then an Army Surgeon serving in Kansas) in the chalk of western Kansas --- this  paper pre-dates Cope's 1872 description of Portheus molossus by over a year).

McClung, C.E. 1908. Ichthyological notes on the Kansas Cretaceous, I. Kansas University Science Bulletin IV 235-246, pls. x-xiii, 10 text-figs.

Newton, E.T. 1877. On the remains of Hypsodon, Portheus and Ichthyodectes from British Cretaceous strata, with descriptions of a new species. Quarterly Journal of the Geological Society of London 33:505-529, Pl. XXII.

Osborn, H.F. 1904. The great Cretaceous fish Portheus molossus Cope. Bull. Mus. Nat. Hist. Vol. 20, Art. 31, pp. 377-381, pl. 10. [AMNH 32219]

Rogers, K., 1991. A dinosaur dynasty: The Sternberg fossil hunters, Mountain Press Publishing Company, 288 pages.

Schwimmer, D.R., J.D. Stewart, and G.D. Williams, 1997. Xiphactinus vetus and the distribution of Xiphactinus species in the eastern United States. Journ. Vert. Paleo. 17(3):610-615.

Shimada, K. and M.J. Everhart. 2004. Shark-bitten Xiphactinus audax (Teleostei: Ichthyodectiformes) from the Niobrara Chalk (Upper Cretaceous) of Kansas. The Mosasaur 7, p. 35-39.

Sternberg, C.H. 1917. Hunting Dinosaurs in the Badlands of the Red Deer River, Alberta, Canada. Published by the author, San Diego, Calif., 261 pp.

Sternberg, C.H. 1922. Field work in Kansas and Texas. Kansas Academy of Science, Transactions 30(2):339-348.

Stewart, A. 1898. A contribution to the knowledge of the ichthyic fauna of the Kansas Cretaceous. Kansas University Quarterly 7(1):22-29, pl. I, II. (Portheus Lowii sp. nov., Daptinus broadheadi sp. nov., Saurocephalus dentatus sp. nov., Protosphyraena bentonia sp. nov., and Protosphyraena sp. nov.) 


Stewart, A. 1898. Individual variations in the genus Xiphactinus Leidy. Kansas University Quarterly 7(3):115-119, pl. VII, VIII, IX, X. (Stewart has a short note on page 115 acknowledging that Xiphactinus Leidy 1870 has priority over Portheus Cope 1872) .


Stewart placed a short note on page 115 acknowledging that Xiphactinus Leidy 1870 has priority over Portheus Cope 1872."Xiphactinus audax Leidy (Proc. Acad. Sci. Phila., 1870, p. 12) has been shown to the a synonym of Saurocephalus Cope (U.S. Geol. Surv., Wyoming, etc. 1872, p. 418). In a letter to Prof. Mudge, dated October 28, 1870, which will shortly be published in the fourth volume of the Kansas University Geological Survey, Cope refers it to Saurocephalus thaumas (Portheus thaumas Cope). After carefully comparing the description and figure of the pectoral spine of X. audax I was led to the same conclusion; and as the genus Portheus was not made known by Cope until 1871 (Proc. Am. Phil. Soc., 1871, p. 173), according to the rules of nonclamature Xiphactinus should have priority."


Stewart, A. 1899. A preliminary description of the opercular and other cranial bones of Xiphactinus Leidy. Kansas University Quarterly 8(1):19-21, pl. X-XI.

Stewart, A. 1899. Notice of three new Cretaceous fishes, with remarks on the Saurodontidae Cope. Kansas University Quarterly 8(3):107-112. (Xiphactinus, Protosphyraena gigas and Empo [Cimolichthys])

Stewart, A. 1900. Teleosts of the Upper Cretaceous. The University Geological Survey of Kansas. Topeka 4:257-403, 6 figs., pls. 33-78.

Stovall, J.W. 1932.  Xiphactinus audax, a fish from the Cretaceous of Texas.  University of Texas Bulletin No. 3201:87-92, 1 pl.

Thorpe, M.R. 1934. A new mounted specimen of Portheus molossus Cope. American Journal of Science, 5th series, 28(164):121-126, 2 fig. 

Walker, M.V. 1982. The Impossible Fossil. University Forum, Fort Hays State University 26: 4pp.

Walker, M.V. 2006. The impossible fossil - Revisited. Kansas Academy of Science, Transactions 109 (1/2), p. 87-96. (.pdf copies available on request).

Woodward, A.S. 1913. On a new specimen of the Cretaceous fish Portheus molossus, Cope. The Geological Magazine 10(12):529-531, Pl. XVIII.

For younger readers, see also:

Cutchins, J. and G. Johnston. 2001. Giant Predators of the Ancient Seas. Pineapple Press, Inc. Sarasota, Fl. 64 pp.

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Adapted from an image of Xiphactinus audax at the University of Kansas Museum of Natural History. Used with permission.

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Photo by Judy Cutchins © 2001 - A 17 foot long Xiphactinus in the Savage Ancient Seas exhibition, Fernbank Museum of Natural History, Atlanta, GA.