Explorations and field-work of the Smithsonian Institution in .. . res havebeen under observation by members of the staff for more than aquarter of a century. In 1905 the late Dr. Frederick W. True beganwork along the Calvert cliffs. Beginning in 1908 and continuingthrough subsequent years, he was assisted by William Palmer, NormanH. Boss, and David 15. Mackie. The writer first visited the Calvertcliffs in 1922 and since then at favorable intervals has continued thesearch for remains of these fossil marine mammals. The fossil bonesfound in this formation are soon freed from the matrix by a ski
Explorations and field-work of the Smithsonian Institution in .. . res havebeen under observation by members of the staff for more than aquarter of a century. In 1905 the late Dr. Frederick W. True beganwork along the Calvert cliffs. Beginning in 1908 and continuingthrough subsequent years, he was assisted by William Palmer, NormanH. Boss, and David 15. Mackie. The writer first visited the Calvertcliffs in 1922 and since then at favorable intervals has continued thesearch for remains of these fossil marine mammals. The fossil bonesfound in this formation are soon freed from the matrix by a skilledpreparator, and the preservation of the skulls is such that the minutedetails of their construction can be studied as readily as those of recentcetaceans. Among the fossil cetaceans found in these exposures, none is moreunusual than the aberrant porpoise, Zarliacliis UagcUator. The skull ofthis porpoise is nearly 4 feet long, and the rostrum is fully five times aslong as the braincase. The extreme stage in the lengthening of the 15 i6 SMITHSONIAN INSTITUTION. Fig. 19.—Fossil-bearing strata in cliff on western shore of Chesapeake Bay,in which are found the bones of various sea-living mammals. SMITHSONIAN EXPLORATIONS, I933 17 rostral part of this skull may represent the culmination uf this sort ofdevelopment in the long-snouted type of porpoise. The vertebralcolumn is sufficiently well known for one to reconstruct the entireskeleton and thus determine the length of the porpoise as approxi-mately 16 feet. Other kinds of long-snouted and short-snouted por-poises are found in these deposits, some of them more frequently thanothers. Associated with these small-toothed whales was an extinctsperm whale, less than one third as large as the living species. In the same seas lived several kinds of extinct whalebone whales,and with one exception all were noticeably smaller than the smallestof the living mysticetes. These early whalebone whales do not possessteeth in their jaws but ha
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectscienti, bookyear1912
