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only showed three digit impressions, which is at odds with the five-toed condition inferred for the original tetrapod. He consequently argued that the five-toed stage might have evolved only later during tetrapod evolution. Alternatively, he suggested that two additional digits might have originally
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impressions, a complex impression and part of a second impression. The complex impression is 84.3 millimetres (3.32 in) in length and 64 millimetres (2.5 in) in width, and has a depth of up to 9 millimetres (0.35 in). Its margins are sharply defined and slightly overhanging the
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impressions. These two impressions taper at one end, and are segmented by constrictions which resemble constrictions between toe pads. A concavity bordering one of the "digit" impressions has been interpreted as a possible third digit impression. The slab is composed of brown-gray
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does not fit what is now known about the anatomy of early tetrapods; that it lacks symmetry and other features expected for a footprint; and that the overhanging margins rather indicate that it is an impression of a rounded object. Lucas argued that this makes
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Cast of the fossil as published by Dudley J. Morton in 1926. A) shows the cast of the original, while B) shows a reconstruction of an assumed missing area (outlined by black dotted line), which adds two additional digit
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Outline drawing (left) and superimposition of a foot skeleton of an early tetrapod (right), by Dudley J. Morton, 1926. This interpretation shows a five-toed configuration of the assumed footprint.
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been impressed between the two larger digits but were not preserved, resulting in a five-toed foot. Morton further suggested that the digits would have been outwards directed during walking.
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by a wide margin from the earliest stages of the transition from an aquatic to a terrestrial habitation", which pushes back the origin of tetrapods well into the
Devonian, and possibly even
278:, with the complex, two or three-toed impression pertaining to a left hind foot and the partial impression to a probable fore foot. This find was therefore the first fossil ascribed to a
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on
October 16, 1896. The note was accompanied by a simple outline drawing. The specimen is part of the collection of the Yale Museum under the specimen number YPM 784.
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impression. The complex impression is horseshoe-shaped, with two elongated impressions joined at their bases, which early workers interpreted as
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occur in the beds the fossil was found in, indicating that the impression formed in a shore environment. The fossil slab itself preserves the
286:, and therefore the oldest such fossil known. Marsh's interpretation was widely accepted until the 1930s. American Paleontologist
182:(land vertebrates) known at the time. Later research, however, argued that the fossil is better interpreted as the impressions of
353:(fossilized feces) of a fish would be as likely as its interpretation as a footprint. American zoologist and paleontologist
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in 1925. Abel concluded that different interpretations are possible, and found that an identification as the impressions of
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was clearly separated from its leg, indicating an elevated position of the body and limbs, and a clear adaptation to
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that has since fallen in disuse. Lucas, in his 2015 review, stated that the fossil is thought to come from the
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in age, i.e. the older part of the Late
Devonian, ca. 383–372 million years ago. Beecher noted that
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agreed with Abel's interpretation, noting that it closely resembles coprolites from the Early
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Williston, Samuel
Wendell (1917). "The phylogeny and classification of reptiles".
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According to
Beecher, the fossil stems from the "Chemung Formation", a
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as a footprint, after studying the specimen during a research visit in
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Marsh interpreted the impressions as the footprints of an
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and a critical review of
Devonian tetrapod footprints".
707:. New York: The MacMillan Company. 1951. p. 1013.
693:(in German). Jena: Gustav Fischer Verlag. p. 77.
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Morton, Dudley J. (1926). "Notes on the footprint of
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341:became the first to question the interpretation of
567:"The origin and evolution of life upon the earth"
190:the earliest published name of a fish coprolite.
161:in a brief note published in 1896, with the only
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294:as the basis of his basal tetrapod group
528:"Amphibian Footprints from the Devonian"
313:. He stated that these features "remove
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264:published a brief note naming the new
154:. The only specimen was described by
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178:, making it the oldest evidence for
305:, in 1926, argued that the foot of
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395:Stratigraphy and paleoenvironment
337:In 1935, Austrian paleontologist
47:Outline drawing of the fossil by
565:Osborn, Henry Fairfield (1916).
298:, which fell into disuse since.
198:The only specimen attributed to
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526:Marsh, Othniel Charles (1896).
170:. Marsh interpreted it as the
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498:10.1080/10420940.2015.1063491
419:, rain drop impressions, and
237:The fossil was discovered by
387:the earliest fish coprolite
16:Ichnogenus of marine reptile
656:American Journal of Science
532:American Journal of Science
480:Lucas, Spencer G. (2015). "
282:(land vertebrate) from the
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691:Vorzeitliche Lebensspuren
202:is a slab containing two
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676:10.2475/ajs.s5-12.71.409
288:Samuel Wendell Williston
552:10.2475/ajs.s4-2.11.374
242:Charles Emerson Beecher
138:is the name given to a
606:The Journal of Geology
571:The Scientific Monthly
448:, Yale digital content
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258:Othniel Charles Marsh
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159:Othniel Charles Marsh
49:Othniel Charles Marsh
401:geological formation
355:William King Gregory
321:. Morton noted that
668:1926AmJS...12..409M
618:1917JG.....25..411W
544:1896AmJS....2..374M
301:American physician
224:History of research
705:Evolution Emerging
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311:locomotion on land
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689:Abel, O. (1935).
652:Thinopus antiquus
269:Thinopus antiquus
172:fossil footprints
167:Thinopus antiquus
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103:Thinopus antiquus
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391:that was named.
368:Spencer G. Lucas
359:lobe-finned fish
303:Dudley J. Morton
290:, in 1917, used
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140:trace fossil
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70:Ichnogenus:
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407:, which is
376:Nova Scotia
262:Yale Museum
194:Description
107:Marsh, 1896
454:References
389:ichnotaxon
351:coprolites
266:ichnotaxon
218:grain size
184:coprolites
144:ichnotaxon
634:140645335
583:0096-3771
506:130053031
417:mudcracks
296:Protopoda
276:amphibian
214:sandstone
180:tetrapods
176:amphibian
150:rocks in
719:Category
482:Thinopus
446:Thinopus
432:Nuculana
424:mollusks
409:Frasnian
385:Thinopus
380:Thinopus
343:Thinopus
323:Thinopus
319:Silurian
315:Thinopus
307:Thinopus
292:Thinopus
284:Devonian
280:tetrapod
216:of fine
200:Thinopus
188:Thinopus
148:Devonian
135:Thinopus
78:Thinopus
25:Thinopus
664:Bibcode
614:Bibcode
540:Bibcode
428:bivalve
260:of the
204:concave
51:, 1896
632:
589:
581:
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486:Ichnos
421:marine
86:, 1896
630:S2CID
587:JSTOR
502:S2CID
252:, in
209:digit
84:Marsh
591:6141
579:ISSN
672:doi
654:".
622:doi
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494:doi
374:of
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