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.

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.

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. 

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.

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) 

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. 

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....

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.

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.

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). 

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.

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."

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.

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). 

2006 PHOTO HERE

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.

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)

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

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.

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. 

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

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.

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.

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.

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.

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.

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

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.

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.