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DECODING COPE'S TEXAS TAXA: Eryops and Dimetrodon natalis

June 15 , 2016

by Ben Creisler

May 29th (a week ago) marked the birthday of the Swiss-born naturalist, geologist, and fossil collector Jacob Boll (1828–1880), best known for his discoveries of Early Permian vertebrates in Texas, first described by American paleontologist/herpetologist/ichthyologist Edward Drinker Cope (1840-1897).

Among Boll's finds were the original fossils for *Dimetrodon*, *Eryops*, and *Diadectes*. Boll's material for *Dimetrodon* in particular proved of special significance to Cope in recognizing the evolutionary importance of early pelycosaur-grade synapsids, both as a primitive early stage of amniotes and as the earliest ancestors of mammals.

Tragically, Boll died at 52, reportedly from a rattlesnake bite while in the field looking for fossils for Cope (although other sources have indicated appendicitis or peritonitis as the cause of death).

As an ichthyologist, Cope named a living catfish species from Texas in Boll's honor (from a specimen collected by Boll): *Amiurus bolli* Cope, 1880--the name is now a junior synonym of *Ameiurus natalis* (Lesueur, 1819). (More about the tricky possible meanings of the species name *natalis* (including Cope's *Dimetrodon natalis*) later!)

For biographical material on Boll:

Louis L. Jacobs, Pia D. Vogel & John Lewis (2012) Jacob Boll, Robert T. Hill and the early history of vertebrate paleontology in Texas. Historical Biology 24(4): 341-348 DOI:10.1080/08912963.2012.683192




Geiser, S.W. 1937. Naturalists of the frontier. Dallas (TX): Southern Methodist University Press.



Texas frontier scientists who uncovered state’s fossil history had role in epic Bone Wars



Moulton, J.M. 1974. A description of the vertebral column of Eryops based on the notes and drawings of A.S. Romer. Mus. Comp. Zool. Breviora. 428:1–44.



*Amiurus bolli* Cope, 1880 (pg. 35)


Cope, E. D. 1880. On the Zoological Position of Texas, Bulletin of the United States National Museum 17: 1-51.


It seems like a good opportunity to look at a few of the now misunderstood names that Cope gave to his Texan Permian vertebrates, including some of Cope's specific names, which were sometimes as innovative (or as cryptic) as his generic names.

Cope rarely gave etymologies or explanations for his chosen names. However, his descriptions of taxa often mentioned a particular anatomical feature or some other special characteristic that closely matched a possible meaning for the Greek or Latin terms used in his assigned names (both generic and specific).

As always, any errors are mine, and corrections or improvements are much appreciated. A list of free links to full pdfs of additional papers is provided at the end.



On the topic of Cope's specific names (and my errors), I need to add a correction to my April 1st post on Cope and the name *Nimravus*...

"Apparently Cope (professional and personal rivalry aside) appreciated Marsh's nomenclatural inspiration and used -avus in the name *Nimravus* to suggest ancestry--the first example of another researcher other than Marsh using -avus in the name of a fossil animal."


In fact, the first use of Latin *avus* "grandfather, ancestor" like a suffix appears to be by Cope himself in 1868 with the specific name *Clidastes iguanavus* Cope, 1868 "(vertebrae) locker iguana ancestor" for a mosasaur:


[*Clidastes* Cope, 1868, from Greek *kleido* "lock up" + Greek suffix *-astes* "one who (does)" ( thus, "one who locks its vertebrae," for interlocking processes (zygapophyses, zygosphens) on its vertebrae]

Note that Cope later described a much more complete mosasaur specimen that he named *Clidastes propython* "before python", which became the main basis for *Clidastes* as a genus and was made the official neotype by the ICZN in 1993.

*Clidastes propython* Cope, 1869:



ICZN petition to make *Clidastes propython* the neotype (1992)


ICZN Opinion 1750 (1993)



Cope's species *Clidastes iguanavus* was based on a single vertebra (now considered indeterminate), which he thought (in rather murky phylogenetic terms) probably indicated "a forerunner of the Iguanian type of Lacertilia" but with "strong relationships" to mosasaurs. The name *Clidastes iguanavus* from 1868 has become fairly obscure--unfortunately, it slipped my mind (my bad, as they say) when I wrote up the April Fools' *Nimravus* post and only concentrated on generic names.

Marsh's much better known (and much more nomenclaturally influential) use of *avus* like a suffix in generic names started in 1871 (*Boavus*, *Iguanavus*, * Lemuravus*, *Tapiravus*, *Viverravus*, *Vulpavus*, etc.) and was meant to suggest evolutionary ancestry.

As it turns out, Marsh's combinations with *avus* were undoubtedly inspired by Cope's earlier 1868 combination *iguanavus* as a species--in fact, pre-rivalry-period Cope even mentioned that the original isolated *iguanavus* vertebra was "found by my friend [!!] Prof. O. C. Marsh, of Yale College..." (Cope 1868, pg. 16).

As a result, Cope's use of *avus* in the generic name *Nimravus* "panther ancestor" in 1879 likely did NOT come in response to Marsh's use of *avus* in generic names to indicate ancestry as I had speculated, since Cope had already used *avus* himself in a similar way in 1868. This removes the possible puzzle of why the nomenclaturally creative Cope would use one of O. C. Marsh's nomenclatural ideas. However, later authors (*Bufavus* Portis, 1885, *Ranavus* Portis, 1885, *Ailuravus* Ruetimeyer, 1891, *Ursavus* Schlosser 1899, *Vespertiliavus* Schlosser, 1887, etc.) almost certainly got the idea for using *avus* combined with an existing generic name from Marsh's generic names rather than from Cope's fairly obscure species *Clidastes iguanavus*. (More on Marsh "borrowing" terms and ideas from Cope a bit later on...)


*Eryops* Cope, 1877 "pulled-back face"

Jacob Boll's best known fossil discovery is the original type material for the large temnospondyl amphibian *Eryops*, including the well preserved complete skull and lower jaw (*Eryops megacephalus* holotype (AMNH 4189)) that Cope first described in 1877. Cope did not give an etymology nor an explanation for the name, but his descriptions provide some clues and seem to best support the following derivation and meaning:

*Eryops* Cope, 1877 "pulled-back face" (from Greek *eryo* "pull, draw, drag" + Greek *ops* "eye, face, appearance"), likely for "quadrate bones produced far backwards," placing the jaw joint articulation well behind the base of the skull

For the range of meanings *eryo* and *ops* could have in Ancient Greek (highlighted in blue in the first links):







The most widely cited etymology for *Eryops* has been based on Colbert's "Dinosaur Book":

"Eryops (ER-ee-ops. From Greek. eryein— "to draw out" — ops— "face"; so named because the greater part of the skull is in front of the eyes.)"


While the Greek source appears to be correct (Greek *eryein* is the infinitive form of *eryo* ("I draw, I pull"), the standard first-person indicative present form of the verb used in Greek lexicons), the explanation for the name (supposedly referring to the part of the skull in front of the eyes) does not match Cope's original description very well. In fact, Cope emphasizes one distinctive detail in particular: the quadrate bones.



Cope, E. D. 1877. Descriptions of extinct Vertebrata from the Permian and Triassic formations of the United States. Proceedings of the American Philosophical Society 17: 182-193.

*Eryops megacephalus* Cope gen. et. sp. nov.

"Char. gen. The details of the structure of this genus are derived from an almost entire cranium with underjaw... The skull is not elongate, and the quadrate bones are produced far backwards..."

And later in the description:

"The quadrate bones extend far posteriorly, and are horizontal above at their distal extremities."


Cope's table of measurements in meters:

"Length of cranium from the extremity of the os quadratum .433

"Length of cranium on middle line .335"

So Cope lists a difference of 9.8 cm extended behind the end of the midline of the cranium, or about 22% of the entire length of the cranium.

Note that Cope's table of measurements does NOT include a measurement of the distance between the eyes and end of the snout, the supposed reason for the name per Colbert.

Cope cited British biologist Louis Compton Miall (1842-1921) for his 1874 study of labyrinthodonts (published 1875) and compared the new *Eryops* skull to some of the taxa Miall described.

Miall, L. C. 1875. Report on the Structure and Classification of Labyrinthodonts. Report of the British Association for the advancement of Science. 44 (1874): 149-192




The proportional length of the region of the face in front of the eyes in *Eryops* would not appear to be particularly notable or distinctive, since some of the amphibians described and illustrated by Miall have much longer snouts or comparatively longer distances between the eyes and the tip of snout. (Not to mention the eye-to-snout-tip facial proportions of crocodilians, which typically exceed those of ancient amphibians.) However, the shifted far back position of the quadrates in *Eryops* relative to the base of the skull WOULD appear to be distinctive compared to Miall's reconstructions of other amphibian skulls.

Cope' s later illustrations of *Eryops* (from 1884) show an almost heart-shaped skull from above, with the quadrate and jaw joint extended well beyond the occiput.


My best hunch then is that Cope intended the name *Eryops* as "pulled-back face" or "drawn-back face" in reference to the distinctive far-back position of the quadrates compared to most other labyrinthodonts--and NOT for the facial region in front of the eyes.


For the record, other (less likely) explanations for Cope's name *Eryops* have been proposed.

'ERYOPS...Literally, "drawn-out eye," referring to the fact that the eye socket is raised up above the surrounding skull' [pg. 52]

William E. Scheele 1954. Prehistoric Animals. World Pub. Co., 1954 - Nature - 125 pages


In Greek, the verb *eryo* also had a second set of meanings in the so-called "middle voice," that is, acting for one's one benefit, formed with particles -mai, -etai, etc. at the end

Greek*eryomai* "protect, guard" (i.e., "I draw toward (or for) myself"), thus *eryo* might be used to mean "protect" or "guard" such as when speaking of armor or when defending someone or something.


Some older 19th century sources suggested that Cope's name *Eryops* meant "protected look"--but I'm skeptical that this was Cope's main idea. The solid, heavy construction of the skull in *Eryops* is similar to other labyrinthodonts and so is a general character of the group, and not distinctive to *Eryops*.

'ERYOPS... [Ety. eruo, I protect; ops, view.] ...'


Miller, S. A. 1889. North American Geology and Palæontology for the Use of Amateurs, Students, and Scientists.


As a clarification side note, a similar-looking name worth noting here is *Eryosuchus* Ochev, 1966 for a Middle Triassic mastodonsaurid temnospondyl from the Donguz River region in the southern Urals of Russia.

*Eryosuchus* Ochev, 1966 "pulled crocodile"; for how the original fossils were literally "pulled" out of the ground

*Eryosuchus* was so-named because the original fossils had to be "pulled" or "extracted" out of the ground with great difficulty, including bringing in a bulldozer with a driver from a nearby construction crew (and destroying a potential archaeological site in the process!). Ochev explained the name as meaning, figuratively, <<с трудом добытый зверь [s trudom dobytyy zver']>> ["hard-gotten beast" (literally "extracted with effort beast")] (Ochev 1976, pg. 54)--in Greek, *eryo* could also mean dragged or pulled away with force or violence. So *Eryosuchus* was NOT named for any resemblance or connection to *Eryops*, which is only distantly related.

For an account of how the original *Eryosuchus* fossils were found and retrieved (and so-named), see Ochev's 1976 nontechnical book "Secrets of the Flaming Hills" (in Russian) about searching for Permian and Triassic fossils in the Urals:

Очев В.Г. 1976. Тайны пылающих холмов. Саратов. [Ochev, V. G. 1976. Secrets of the Flaming Hills. Saratov University Press, Saratov] 95 pp.

Excerpts in Russian describing the discovery and recovery of *Eryosuchus*:


Full book available as a free download here:

in DjVu:



Unfortunately (for now at least), Ochev's original 1966 scientific description of *Eryosuchus* does not appear to be available online:

Очев В.Г. 1966. Систематика и филогения капитозавроидных лабиринтодонтов. Саратов Сарат. универ. [Ochev, V. G. 1966. Systematics and phylogeny of capitosauroid labyrinthodonts. - Saratov University Press, Saratov]: 184 pp.


*Dimetrodon natalis* and Cope's Earliest Reptiles

Jacob Boll's vertebrate fossils from the Permian of Texas (collected between 1877 and 1880) proved of major historical importance to a more accurate understanding of the evolution of early tetrapods and the origin of mammals. Based on Boll's specimens, Cope first recognized that the earliest synapsids retained a number of primitive skeletal features found in amphibians but also provided the founding link in the origin of mammals. Both insights came to Cope in 1878 and remain essentially valid according to modern understandings of evolution and phylogeny. A bit of history...

Cope and the Rhynchocephalia

The reptilian group Rhynchocephalia "beak heads" was first proposed by German-born British zoologist Albert Günther (1830-1914) in 1867 to separate the extant tuatara *Hatteria* [= *Sphenodon*] from other reptiles, in particular from lizards (Lacertilia), based on a number of distinctive anatomical features such as amphicoelous vertebrae, two temporal bars on the skull, and lack of a copulatory organ. However, Günther saw the *Hatteria* as a peculiar mix of low and high features (with uncinate processes on its ribs as in crocodilians and birds) and did not characterize the Rhynchocephalia as necessarily more primitive than other reptiles, although the amphicoelous vertebrae were more characteristic of ancient extinct saurians, and were now only present in the "degraded" "Gekotidae" (other living lizards have procoelous vertebrae) .

Günther, Albert (1867) Contribution to the anatomy of Hatteria (Rhynchocephalus, Owen). Philosophical Transactions of the Royal Society of London 157: 595-629


Cope published many reclassifications of reptiles over the course of his work, and notably introduced the major groups Archosauria (1869), Theromorpha (1878), and the Cotylosauria (1880).

In his 1871 classification of reptiles, Cope revised the Rhynchocephalia to include most of the early reptiles from the Permian and Triassic that Huxley had classified as Lacertilia, distinguished from lizards mainly by flat or biconcave vertebrae. (Cope interpreted the biconcave vertebrae of geckos as merely "embryonic" for the normal lizard form (procoelous when fully developed).) Importantly, for Cope the only reptile group present in the Permian was the Rhynchocephalia, seen as the most generalized type (table pg. 243).


(pages 241-242)

Cope, E. D. 1871. On the homologies of some of the cranial bones of the Reptilia, and on the systematic arrangement of the class. Proceedings of the American Association for the Advancement of Science 9: 194–247.


In 1875 Cope described two new genera found in Vermillion County, Illinois that he thought were related to the Rhynchocephalia as he had recently redefined it, but he was uncertain whether they dated from the Permian or Triassic (in fact, they were Pennsylvanian in age). The fossils would be the first evidence of the Rhynchocephalia known from North America.

*Cricotus* "ringed (vertebrae)" (Greek *krikotos* "ringed, made of rings"), mainly based on discoidal biconcave caudal vertebrae with annular articular edges (material, in fact, belonging to an anthracosaur, now a nomen dubium.).

"The lateral borders of the posterior articular face are expanded backwards, and articulate with a bevel of the corresponding edge of the anterior articular extremity."

Note that much more complete anthracosaur material from the Early Permian of Texas that Cope identified as *Cricotus* was reclassified as belonging to *Archeria* Case, 1915 by Romer (1957).



*Clepsydrops* "hourglass-look (vertebrae)" (Greek *klepsydra* "hourglass" (funnels connected by a small opening) + Greek *ops* "eye, face, appearance"); for deeply biconcave vertebrae (genus originally based on ophiacodontid material from Illinois, dating from the Pennsylvanian (Upper Carboniferous)).

"They are deeply biconcave, the articular cavities being funnel-shaped and continuous, thus perforating the entire length of the centrum."


Cope, E. D. 1875. On fossil remains of Reptilia and Fishes from Illinois. Proceedings of the Academy of Natural Sciences of Philadelphia 1875 27(2): 404-411.

[Illustrated along with other *Clepsydrops* species from Illinois:

http://www.biodiversitylibrary.org/page/6703778#page/197/mode/1up ]

Cope described two additional species of *Clepsydrops* from Illinois in 1877, now fully convinced the genus belonged to the primitive Rhynchocephalia.

Cope, E. D. 1877. On the Vertebrata of the bone bed in eastern Illinois. Proceedings of the American Philosophical Society 17: 52-63.


Shortly afterwards in 1877, Cope described new material from Texas, discovered by Jacob Boll, which, in addition to *Eryops* noted above, included what Cope identified as another species of *Clepsydrops* (pg. 193). (Cope still thought the material may have dated from the Triassic rather than from the Permian.)

*Clepsydrops limbatus* "bordered" (Latin *limbatus* "bordered, having borders"); for "rim-like borders on the articular extremities" of the centrum. [Now *Dimetrodon limbatus*, the type species]

Cope, E. D. 1877. Descriptions of extinct Vertebrata from the Permian and Triassic formations of the United States. Proceedings of the American Philosophical Society 17: 182-193.



On April 5, 1878, Cope gave a talk before the American Philosophical Society in Philadelphia that discussed more new material from the Permian of Texas (presumably nearly all collected by Boll). Cope now was convinced that the fossils dated from the Permian and not from the Triassic. He classified the reptiles as members of the Rhynchocephalia and introduced the term "intercentrum" for "intervertebral elements"--a separate wedge-like bone inserted between the lower parts of the centra along the vertebral column-- that he had identified in the remains of both amphibians and reptiles from the Permian beds. He also noted the double articulation of the ribs with the vertebrae in some of the specimens, and mentioned evidence of elevated neural spines likely forming a basilisk-like fin in the Texas *Clepsydrops* and the new genus *Dimetrodon*. On April 18, 1878, he gave the talk again before the National Academy of Sciences in Washington, D.C. A notable presence in the audience this time was his no longer "friend," O. C. Marsh (1831-1899).

Now alerted by Cope to the importance of Permian vertebrates from western North America, Marsh rushed into print a few weeks later in his personal venue journal the American Journal of Science with short descriptions of some incomplete fossil material that had been sent to him from the Permian of New Mexico, collected by David Baldwin. He erected the new genera *Nothodon*, *Ophiacodon*, and *Sphenacodon*, which he identified as all members of the "Rhynchocephala." He also mentioned the presence of "intercentral bones," but attributed the term to Hermann von Meyer, and noted as well biconcave vertebrae and double rib articulations.

Marsh, O.C. (1878). Notice of new fossil reptiles. American Journal of Science 3 (15): 409–411.


Meantime, Cope's introduction of the term "intercentrum" had appeared in print on April 22, in a short note in the May issue of his own journal American Naturalist. (1878: 319)


Another short note in the same American Naturalist (pg. 327) briefly named and described a new fauna from Texas.


A much more detailed discussion of the new finds appeared in the Proceedings of the American Philosophical Society, published May 8, 1878, based on Cope's April 5, 1878 presentation before the organization.

Cope, E. D. 1878. Descriptions of extinct Batrachia and Reptilia from the Permian formation of Texas. Proceedings of the American Philosophical Society 17: 505-530


In June of the same year Cope criticized Marsh over his rival's May 1878 paper about Permian tetrapods from New Mexico, which clearly included ideas and terms (uncredited) from Cope's April talk before the National Academy of Sciences.

Cope, E. D. 1878. Professor Marsh on Permian reptiles. American Naturalist 12: 406-408.




Cope's May 1878 paper in the Proceedings of the American Philosophical Society introduced a number of important taxa from the Early Permian. Many of the generic names remain valid, listed here with a passage from the original description that suggests Cope's reason for the name (none of the names were directly explained):

*Bolosaurus* "lump (tooth) lizard" (Greek *bolos* "lump, nugget" + Greek *sauros* "lizard") [Parareptilia]

"Teeth ... with the crowns expanded transversely to the axis of the jaws. The crowns swollen at the base, and with low apex, divided vertically into two equal portions"


*Diadectes* "cross-biter" (Greek *dia* "across, through" + Greek *dektes* "biter") [Reptiliomorpha]

"Teeth with short and much compressed crowns, whose long axis is transverse to that of the jaws" (pg. 505)


*Dimetrodon* "two-measure tooth" *Greek *di-* two, twice + Greek *metron* "measure" + Greek *-odon* "tooth") [Synapsida]

"The anterior two teeth of the maxillary bone are larger than those that follow, the anterior exceeding even the first incisor. The other maxillaries are smaller and sub-equal, excepting the last two, which are the smallest"


*Empedocles* "firm-set (vertebrae) glory" (from Greek *empedos* "firm-set, fixed in place, steadfast" + Greek *klees* "glory, fame") [Reptiliomorpha]

For interlocking processes on the vertebrae that help strengthen and hold the spine more rigid. The name is a pun on the name of a famous ancient Greek philosopher Empedocles (c. 492—432 BCE) (5th century BCE); name preoccupied and replaced with the name *Empedias* Cope, with a similar etymology

"The neural arches present important differences. There is on the posterior aspect, below the zygapophyses a well developed hyposphen, and on the anterior face a correspondingly strong hypantrum... The zygapophyses are much elevated and spread apart in *Empedocles*, and are connected together back to back."


*Pariotichus* "cheek wall" (Greek *pareia*, "cheek, cheek-piece (on a helmet)" + Greek *teikhos* "wall") [Microsauria]

"the zygomatic arch extends low down, producing a resemblance to certain tortoises"


*Parioxys* "sharp cheek" (Greek *pareia* "cheek, cheek-piece (on a helmet)" + Greek *oxys* "sharp, acute" [Temnospondyli]

(Cope used Pario- (from *pareia* "cheek") in a number of generic names to refer to the post-orbital region and not just the zygomatic arch (cheekbone) as such.)

"The external border of the epiotic next the auditory notch is acute,"


*Trimerorhachis* "three-part spine" (Greek *trimeres* "three-part" + Greek *rhakhis* "spine") [Temnospondyli]

"The centrum is represented by three cortical ossifications of the chorda-sheath, a median inferior, and two lateral."


*Zatrachys* "very rough (skull)" (Greek *za-* "much, very" + Greek *trakhys* "rough") [Temnospondyli]

"The maxillary and other bones are characterized by their strong sculpture, in the former the ridges being developed into prominent tubercles in various places."


A number of Cope's specific names alluded to the iron-rich red beds in which the fossils were found:

*erythroliticus* "belonging to the red stone" (*Epicordylus erythroliticus* = Eryops)

*ferricolus* "iron dweller" (*Parioxys ferricolus*)

*sideropelicus* "belonging to the iron-clay" (*Diadectes sideropelicus*)

Cope's other specific names highlighted details of anatomical features in fairly conventional ways ("striated," "triangular," "strong," "short-faced," etc.), although *rapidens* "turnip tooth" (Latin *rapum* "turnip") and *fritillus* "dice box" can be noted.


*Clepsydrops natalis* (now *Dimetrodon natalis*)

The most important specimen from Texas that Cope noted in his May 1878 paper was a partial skeleton that he made the type of *Clepsydrops natalis*, under the assumption that the new species belonged to the genus *Clepsydrops*, first found in Illinois (ophiacodontid material that, in fact, dated from the Pennsylvanian, not from the Permian as Cope had come to believe). Although not complete, the fossil remains were the most representative material found so far of a reptile from the Texas Permian beds, and included much of the skull, a humerus, parts of the dorsal and caudal vertebrae, and most importantly, the complete pelvis along with much of the hind limb. The species was later transferred to *Dimetrodon* (Romer 1936). [A. S. Romer. 1936. Studies on American Permo-Carboniferous reptiles. Problems of Paleontology 1:85-93.]

Type specimen: AMNH 4110, partial skeleton (of a juvenile); type locality: Mount Barry, 12 (Admiral Formation), in Artinskian terrestrial shale in Admiral Formation of Texas.


Case illustrated the specimen in 1907:

Case, E.C., 1907. Revision of the Pelycosauria of North America. Carnegie Institution of Washington, Publication 55, 176 p.

Plates 4, 5, 6




Cope (1878) noted in particular the unusual construction of the ischia:

"The ischium is a remarkable bone. It is greatly produced anteriorly and posteriorly to the acetabulum, in forming with that of the opposite side, a keeled boat-shaped body..."

Based mainly on this specimen (along with the new *Dimetrodon incisivus*), Cope erected the group Pelycosauria "pelvis lizards" (Greek *pelyx* (genitive *pelykos*) "basin, pelvis"), proposed as a division of the Rhynchocephalia ("beak heads"), and thus the earliest known group of reptiles.

"Of the general affinities of this genus [*Clepsydrops*] it is only necessary now to state that my reference of it to the Rhynchocephalia is confirmed. It differs from the recent species of the order in the absence of quadrato-jugal arch, and the remarkably developed ischia. On this account I refer to *Clepsydrops* and its allies as a distinct suborder under the name of Pelycosauria."

Unfortunately, Cope's choice of the specific name *natalis* was not explained and his reason for the name is not immediately obvious based on the description of the specimen itself. Here's my best hunch:

*natalis* "natal (stage)" (Latin *natalis* "pertaining to birth, natal"): likely for how the vertebrae in *Clepsydrops* and other pelycosaurs (then seen by Cope as early "rhynchocephalian" reptiles) represented the primitive beginning (figurative "natal") stage of development in the evolution in reptiles, still resembling ancient amphibians in having biconcave centra along with intercentrum bones.

Another possible interpretation might be a reference to the early ("natal") stage of mammal evolution. However, it appears that Cope in April and May 1878, when he announced *Clepsydrops natalis* in public and then in print, had not yet fully recognized the Pelycosauria as ancestral to mammals, an insight that came a few months later.


Cope's theses at the end of the same May 1878 paper (pg. 350) may provide a clue to *natalis*: The Permian land vertebrates consisted of "Rhynchocephalian reptiles and Stegocephalous Batrachia," both with "imperfect" (i.e., not fully evolved) vertebrae that were "deeply amphicoelous or notochordal." In addition, "in the primitive land Vertebrata of the Permian, the place of the vertebral centrum was occupied by two elements, the centrum and intercentrum." *Clepsydrops natalis* had deeply amphicoelous vertebrae (as expressed in its original generic name) and intercentra on the dorsal and caudal vertebrae, thus representing the earliest primitive (and "imperfect") condition in reptiles, resembling amphibians.

Without an explicit statement from Cope, however, it remains possible that he chose *natalis* to mean something else. In fact, *natalis* has been used in a number of distinct ways as a specific name in zoological nomenclature. It may be worth taking a bit of a side trip to clarify the issue.


In classical Latin, *natalis* was an adjective derived from *natus* "birth" that could mean "natal, related to birth; native, original to a place; innate." When used as a masculine noun, it could mean "birthday of a person, festival of a god, founding date of a city" and also "birthplace."


As a proper name, Natalis was used in ancient Roman society both as a man's given name and as a family surname, and was also the name of a deity presiding over birth. With the adoption of Christianity, Natalis came to mean Christmas (short for Dies Natalis Domini (or Christi) "Birthday of the Lord (or Christ)"), and became the source of Noel in French and Natal in Portuguese.

In zoological nomenclature, *natalis* has been used in particular to refer to either the Natal region of South Africa (sighted and named by Portuguese explorer Vasco de Gama on Christmas Day in 1497): *Nataliconus natalis* G.B. II Sowerby, 1858 (a gastropod) , or to Christmas Island (discovered on Christmas Day in 1643 by the English explorer William Mynors) *Ninox natalis* Lister, 1888 (a hawk-owl).

In other cases, it may refer to the birthday of a person, as with the urochordate *Slyela natalis* Hartmeyer, 1905, named in a Festschrift to celebrate the 80th birthday of the German zoologist Karl August Möbius (1825-1908), for a specimen Möbius had collected at the island of Mauritius (nowhere near Natal or Christmas Island).

In the case of *Clepsydrops natalis*, there does not appear to be any obvious local geological, stratigraphic, or geographical feature in Archer County in northeastern Texas that would explain *natalis* (the Navidad [Christmas] River is in southern Texas, for instance). Similarly, none of the local indigenous peoples have names that would fit with *natalis* (unlike *Dysganus peiganus*, for the Piegan Tribe in Montana, for example). There is no obvious association with the Christmas holiday, a birthday, a commemoration, or an institutional anniversary.


There are other sources of *natalis* in Neo-Latin nomenclature and terminology that are not found in classical Latin.

The ichnospecies *Striatichnium natalis* Walter, 1982, was created for tracks made by a swimming arthropod (tracks first described from the Permian of Germany) with *natalis* in this case derived (not quite according to classical Latin grammar rules) from the Latin verb *nato* "swim" after the term Natichnia for swimming tracks of invertebrates [<<Nach der Deutung als Schwimmfährten (Natichnia) von Invertebraten>>].

Cope said nothing about *Clepsydrops* being a supposed swimmer, and very likely would have used the grammatically correct Latin form *natans* "swimming" to express the idea rather than *natalis*.


There is another, even odder Neo-Latin derivation that might possibly explain Cope's *natalis*.

The Yellow Bullhead catfish species *Ameiurus natalis* was mentioned above as the valid name for Cope's proposed *Amirurus bolli* in honor of Jacob Boll. A check of current online sources and reference books typically gives the following explanation for the specific name:

*natalis* "having large buttocks"




In the case of the catfish species at least, this turns out to be a bizarre misreading of *natalis* (a fish with buttocks?!!) that deserves to be corrected.

Tracing the story of the species name *natalis* here in its historical context provides a simple, and very different, explanation for the name.

Simon-Barthélemy-Joseph Noël de la Morinière (1765-1822) was a noted French ichthyologist and fisheries expert. Of historical note, Noël wrote to Thomas Jefferson in 1813 to obtain information on fishing and fisheries in the United States for a proposed book. The text of the letter can be seen here with an English translation and a short biography of Noël:


Noël's 1815 book in French on the history of fishing and fisheries in Europe and North America is available here:

Noël, S.B.J. (1815) Histoire générale des pêches anciennes et modernes, dans les mers et les fleuves des deux continens [General History of Ancient and Modern Fishing, in the Seas and the Rivers of the Two Continents] (Paris, Imprimerie royale, 1815)


Earlier, in 1802, the French naturalist Count Lacépède (1756-1825) had published his own book "Histoire naturelle des poissons" [Natural History of Fishes], in which he honored Noël with a new species, citing his important work:

I. LE SCOMBÉROÏDE NOËL. (*Scomberoides Noelii*.)



When the French naturalist Charles Alexandre Lesueur (1778--1846) published a paper in 1819 on fish species from "Haut Canada" [Upper Canada] (and a bit beyond) in North America, he named a new species of catfish:

"6. PIMELODE NOËL. (*P. natalis*)" (pg. 154) [*Pimelodus natalis*, now *Ameiurus natalis* (or sometimes *Ictalurus natalis*)]


Lesueur did not explain the specific name, but there is little doubt that his readers at the time would have understood Noël (and thus *natalis*) as a reference to the then famous French ichthyologist Noël de la Morinière.

[I can't find any association between Cope and someone named Noel that would be indicated by *Clepsydrops natalis*. Cope typically used either a genitive case (*vinslovii* for Winslow) or an adjectival suffix such as -(i)anus (*dollovianus* for Louis Dollo) to honor individuals in specific names.]


Later in the 19th century, English anatomists began using the term "natal" to refer to the buttocks, based on the completely different Latin word *nates* "buttocks, rump, haunches": "natal callosities" in certain monkeys, "natal fold" or "natal cleft" in humans, etc.


This second, modern Neo-Latin meaning for natal (from *nates*) somehow became the basis for the etymology *Ameiurus natalis* in an official U.S. government-published reference work (the source of the modern wrong etymologies online and in books):

Jordan, D.S. and B.W. Evermann. 1896. The Fishes of North and Middle America: a Descriptive Catalogue of the Species of Fishlike Vertebrates Found in the Waters of North America North of the Isthmus of Panama. Bulletin of the United States National Museum No. 47 (Part I). U.S. Government Printing Office



"...(*natalis*, having large nates or buttocks)" (pg. 139)


When Jordan and Evermann compiled their book, they apparently did not have access to Lesueur's original description and guessed at the etymology. (Classical Latin did NOT have a word *natalis* derived from *nates* that I can find, and only used *natalis* as derived from *natus* "birth.")

An attempt to correct this old error appeared online in December 2015 on a fish etymology website run by an independent researcher, but, unfortunately, it missed the original intended reference to the French ichthyologist Noël and suggested a possible meaning related to Christmas because of the fish's sometimes red and green coloration.



Although "having big buttocks" on a fish doesn't make much sense, a possible reference to buttocks cannot be completely ruled out for Cope's *Clepsydrops natalis*, in as much as Cope thought the construction of the pelvis, and in particular the ischia, was important and distinctive. However, there are good reasons to doubt such a meaning:

1) The term *nates*"buttocks, rump" properly refers to fleshy tissues rather than to bones.

2) Greek had a word *ischiadikos* to refer to the ischia or the hips, so Cope could have used the more appropriate existing term *ischiadicus* (or maybe the Latin-derived equivalent *coxalis* (from Latin *coxa* "hip bone") to refer to the ischia or hips rather than *natalis* obscurely derived from *nates* "buttocks" instead of from *natus* "birth."

3) Cope's name Pelycosauria "pelvis lizards" already highlighted the distinctive construction of the pelvis in *Clepsydrops* and *Dimetrodon*.


My best hunch remains that Cope chose *natalis* in refer to a figurative "natal" stage of evolutionary development, especially reflected in the vertebrae in pelycosaurian reptiles such as *Clepsydrops*, which still shared some primitive features with amphibians. Cope developed this idea more fully in a number of later papers. (See Additional References at the end.)


On November 7, 1878, based on additional fossil material from Texas (again, provided by Jacob Boll), Cope gave another presentation before the National Academy of Sciences, this time introducing the new group Theromorpha "mammal forms" (Greek *ther* "beast" [=mammal] +Greek *morphe* "form, shape" + -a (neuter plural ending)), distinct from the Rhynchocephalia. The new Theromorpha included Cope's Pelycosauria (now removed from the Rhynchocephalia) and Owen's Anomodontia (1860). Cope characterized the Theromorpha as "probably ancestral" to mammals. The construction of the scapular arch and pelvic arch in pelycosaurs, along with other details of the limb bones, resembled those of mammals, especially monotremes such as the echidna. ("In the genus *Dimetrodon* the coracoid is smaller than the epicoracoid, as in Monotremes.>>)

Cope, E. D. 1878. The Theromorphous Reptilia. American Naturalist 12: 829-830.


Cope's more detailed treatment of his new Theromorpha did not appear until 1880.

Cope, Edward Drinker. 1880. Second contribution to the history of the Vertebrata of the Permian formation of Texas. Proceedings of the American Philosophical Society 19: 38-58.


[NOTE: Cope later replaced the name Theromorpha Cope, 1878 with the similar-looking name Theromora Cope, 1889, unexplained but perhaps meant as "mammal destinies" from Greek *mora* (also *moira*), meaning "division, lot; fate, destiny," being the group ancestral to mammals. Cope considered the name Theromorpha preoccupied, although apparently not by a zoological name (possibly by the old medical term "theromorphia" (an abnormality in humans resembling a lower animal)?.] See:

Cope, E. D. 1889. Batrachia of North America. (pg. 13)



The two Thermomorpha papers dating from 1878 and 1880 also gave the first description of a species Cope called *Dimetrodon cruciger* (Latin: "cross-bearer") from Texas, found without a skull, and which had tall dorsal spines with branching structures jutting out laterally on each side (unlike the smooth-sided spines in other *Dimetrodon* species), including a distinctive "cruciform process" near the base of the spines, :

"In this species the spine sends off, a short distance above the neural canal, a pair of opposite short branches, forming a cross. " (1878: 830)

Cope later included the species *cruciger* in his new genus *Naosaurus* "ship lizard" (Greek *naos* "ship"), named (rather fancifully) for the jutting processes on the raised dorsal spines, analogous to yardarms on the masts of sailing ships:

(more probably) "....the yardarms were connected by membrane with the neural spine or mast, thus serving the animal as a sail with which he navigated the waters of the Permian lakes."


For a drawing by Cope showing the supposed skin sails on a spine, see the upper left-hand corner of his sketch of *Dimetrodon incisivus* and "*Dimetrodon*" *clavatus* on pg. 97 in the short pdf excerpt from the book Charles R. Knight: The Artist Who Saw Through Time:


This species (*cruciger*) would only be recognized much later as belonging to Cope's genus *Edaphosaurus* Cope, 1883 "pavement (tooth) lizard" (Greek *edaphos* "ground, foundation, pavement"), first described and named based on an isolated skull and lower jaw, notable for densely packed, small teeth that formed a "dental pavement" (Cope's phrase) on each side in the back of the upper and lower jaws. The type material skull and lower jaw for *Edaphosaurus* was collected after the death of Jacob Boll, probably by W. F. Cummins.




In the descriptive table for *Edaphosaurus*, Cope used the term "dental pavement":

"Width of ramus at dental pavement... Length of superior dental pavement..." (pg. 450)


Cope, E. D. (1882). Third contribution to the History of the Vertebrata of the Permian Formation of Texas. Proceedings of the American Philosophical Society 20: 447–474.

(NOTE: Cope's name *Edaphosaurus* has been widely misread as "earth lizard," "soil lizard," or "foundation lizard," based on other meanings for Greek *edaphos*, a topic for another post. Cope clearly meant the name *Edaphosaurus* as "pavement lizard' for its dense arrangement of small grinding teeth, similar to Buckland's old name *Edaphodon* Buckland, 1838 "pavement tooth" and Cope's earlier name *Myledaphus* Cope, 1876 "grinding pavement," both for genera of fossil fishes with pavement-like arrangements of small crushing teeth. The word "pavement" is used in both descriptions:

*Edaphodon* (Greek *edaphos* "pavement" +* -odon* "tooth")

(teeth) "disposed so as to form a PAVEMENT, arming the interior of the mouth with powerful instruments for crushing shells"


Buckland, William. 1838. On the discovery of fossil fishes in the Bagshot sands at Goldworth Hill, 4 miles north of Guildford. Proceedings of the Geological Society of London 2(58): 687-688


*Myledaphus* (Greek *mylo* "grind" + *edaphos* "pavement")

"The crowns form a PAVEMENT having a regularly hexagonal outline."


Cope, E. D. 1876. Descriptions of some vertebrate remains from the Fort Union beds of Montana. Proceedings of the Academy of Natural Sciences of Philadelphia 28: 248-261


Cope apparently named *Clepsydrops natalis* in 1878 BEFORE he had recognized the Pelycosauria as likely ancestral to mammals (announced in November 1878), so, as mentioned above, a meaning "natal" for *Clepsydrops natalis* would not appear to refer to the "birth" of mammals but rather to the most primitive ("natal") stage of development of reptiles (supposedly as the earliest members of the Rhynchocephalia). However, Cope already recognized some resemblance between the Pelycosauria and mammals in his May 1878 paper. He noted:

"Prof. Owen has named a group of Triassic and Permian reptiles the Theriodonta, characterized by the mammal-like differentiation of the incisor and canine teeth. The animals thus referred by Prof. Owen probably enter my suborder of Pelycosauria..." (pg. 529)

In the same May 1878 paper he also erected the new genus *Theropleura* "mammal rib" (Greek *ther* "beast [= mammal]" + *pleura* "rib" ) [= *Ophiacodon*], alluding to the double articulation for the rib (with a separate costal articulation on both the diapophysis and on the centrum), again, similar to mammals.

Confusingly, Cope's various early versions of the Pelycosauria and Theromorpha included, in addition to synapsids such as *Dimetrodon* and *Ophiacodon* [*Theropleura*], other species that are now classified as lepospondyls (*Diplocaulus*), microsaurs (*Pariotichus*), reptiliomorphs (*Diadectes*, *Empedias*, *Lysorophus*), and parareptiles (*Bolosaurus*)--thus some of the perceived mammal-like qualities and features of the Pelycosauria originally were not strictly based on synapsids.


Cope, E. D. 1881. Catalogue of Vertebrata of the Permian Formation of the United States. American Naturalist 15:. 162-164.



Cope, E. D. 1888. Systematic catalogue of the species of Vertebrata found in the beds of the Permian epoch in North America, with notes and descriptions. Transactions of the American Philosophical Society 16: 285-297.


Tales of the "Bones Wars" between Marsh and Cope typically focus on dinosaurs, where Marsh carried the day in terms of still accepted taxa and valid names (although ICZN petitions to change the type material or type species are underway for *Allosaurus* (Case 3506), *Stegosaurus* (Case 3536), and *Diplodocus* (Case 3700) (already changed for *Anchisaurus* (Opinion 2361 (Case 3561))).

Although Marsh gets credit for the genera *Ophiacodon* and *Sphenacodon*, and established the families Ophiacodontidae and Sphenacodontidae (the clade that includes Cope's *Dimetrodon*), Cope emphatically "won" the bone and taxa wars for North American Early Permian tetrapods, based not only on fossils found by Jacob Boll, but on dozens more found by William F. Cummins (1840-1931), who became Cope's main Texas collector after Boll's death in 1880. Cope's pioneering insights into early amniotes and the ancestry of mammals based on these discoveries remain a benchmark in the history of paleontology and for studies of evolution.



For a summary of the history of the discovery and early descriptions of the Pelycosauria, see:

G. Baur and E. C. Case (1899) The History of the Pelycosauria, with a Description of the Genus Dimetrodon, Cope. Transactions of the American Philosophical Society New Series. 20(1): 5-62 DOI: 10.2307/1005488



Brocklehurst, Neil (2015) The Early Evolution of Synapsida (Vertebrata, Amniota) and the Quality of their Fossil Record. DISSERTATION for Humboldt-Universität zu Berlin



Cope, E. D. 1888. On the intercentrum of the terrestrial Vertebrata. Transactions of the American Philosophical Society 16: 243-253




Cope, E. D. 1882. Third contribution to the history of the Vertebrata of the Permian formation of Texas. Proceedings of the American Philosophical Society 20: 447-461



Cope, E. D. 1883. Fourth contribution to the history of the Permian formation in Texas. Proceedings of the American Philosophical Society 20: 628-636.



Cope, E. D. 1884. Fifth contribution to the knowledge of the fauna of the Permian Formation of Texas and the Indian Territory. Proceedings of the American Philosophical Society 22:. 28-47.



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