While performing extensive research on the Paleozoic shark genus Petalodus, I uncovered many holotype specimens. Yet, in searching, there are still a couple that I have not been able to locate. Not finding some is not surprising, all the missing holotypes were described during the 19th century and the 1800s.

I have spent the most time hunting for Petalodus ohioensis, a tooth that is the default genus for North American Pennsylvanian-aged teeth. Safford published his new species in a little-known publication, which many authors failed to reference as they described other unique species. He did not deposit the tooth in a known institution, and today we know only the whereabouts of casts. The Yale Peabody Museum has a cast of the tooth in their collections, which until recently was the best representation of the holotype known to researchers. Itano & Carpenter (2020) found a much better cast of the holotype at the Field Museum, donated by O.P. Hay in 1896.

I obtained a copy of James M. Safford’s handwritten fossil cabinet inventory from his time at Vanderbilt University in Nashville, Tennessee. Unfortunately, the inventory made no mention of Petalodus. Safford taught into his 70s, and the location of his specimens is unknown after he retired.

The Seven Lost Holotypes of Petalodus.

The highest-profile specimen of the group below is Petalodus ohioensis. Authors have recorded several examples of the species over the past century and a half. Reports of the others are rare.

SpeciesLocation
Petalodus arcuatus 1870 St. JohnUnknown. Illustrated in 1870.
Petalodus curtus 1870 Newberry and WorthenUnknown. The pair illustrated and described these in 1870 for the Geological Survey of Illinois. The reported specimen was from Otter creek, Jersey county, Illinois.
Petalodus hybridus 1875 St. John and WorthenA species from the 1875 Geological Survey of Illinois, Volume 6. One of two teeth from the collection of Sir William Cornelius Van Horne. After his passing, the collection went to the University of Chicago. The holotype ID might be UC 27368.
Petalodus knappi 1879 NewberryNewberry erected the species in Indiana from species from two locations. If there are specimens, they are likely at The American Museum of Natural History. Their online catalog, however, shows no results for this species.
Petalodus ohioensis 1853 SaffordThis tooth is known today from an illustration and two casts. One cast resides at the Yale Peabody Museum (YPM PV 2861), the other at The Field Museum (FMNH PF 673). The Field Museum cast was unknown until recently when Itano & Carpenter (2020) found its location after extensive research. This cast is of much greater detail than the Yale cast. Unfortunately, the original specimen is lost, perhaps retained in Safford’s collection.
Petalodus proximus 1875 St. John and WorthenThis species is one of two teeth from the collection of Sir William Cornelius Van Horne. The collection is now at the University of Chicago.
Petalodus sagittatus 1843 (Agassiz)An illustration is available, yet it appears non-congenic for Petalodus.

Gallery of Petalodus ohioensis specimens.

Petalodus ohioensis. A specimen from the Pine Creek limestone, Kittanning, PA.
Petalodus ohioensis, CG-0347. A specimen from the Pine Creek limestone, Kittanning, PA.
Detail of the distal crown tongue of Petalodus ohioensis.
Petalodus ohioensis, CG-0347. Details of the distal crown tongue of a specimen from the Pine Creek limestone, Kittanning, PA.
Petalodus ohioensis. The contrast is enhanced using ammonium chloride.
CG-0055 Petalodus ohioensis. The contrast is enhanced using ammonium chloride. Scale bar = 1 cm.
Petalodus ohioensis. Detail of the distal crown tongue. The contrast is enhanced using ammonium chloride.
CG-0055 Petalodus ohioensis. Detail of the distal crown tongue. The contrast is enhanced using ammonium chloride. Scale bar = 1 mm.

More Reading about Petalodus

References

  • YPM 2861 Collections Page – Yale Peabody Museum of Natural History.
  • Itano, W., Carpenter, K, 2020, High-quality Casts of the Missing Holotype of Petalodus ohioensis Safford 1853 (Chondrichthyes, Petalodontidae) at the Field Museum of Natural History and their Bearing on the Validity and Priority of the Species, Geology of the Intermountain West, V. 7, pp. 197-203.
  • Knowles, V., 2010, William C. Van Horne: Railway Titan, p. 25.
  • Safford, J.M., 1853, Tooth of Getalodus [sic] ohioensis, American Journal of Science and Arts, V. 16, No. 46, p. 142.