vonian sea. Plates of the ostracoderms, 

 Protaspis and Cardipeltis, proved to be so 

 common that soon we were collecting 

 only the best specimens. Among the 

 scattered plates we did discover a few 

 complete, articulated Protaspis, and some 

 of these were juveniles only about three 

 inches long. Entire specimens are most 

 unusual in this family, and babies have 

 not been reported before. Arthrodire 

 plates were also common and appeared 

 to belong to several different genera. 



Besides these known forms, we found 

 an occasional large, rounded scale with 

 a glossy surface punctured with many 

 minute pores; these we attributed at first 

 to the lobe-finned fishes or Crossoptery- 

 gii. Also we found one or two fragments 

 of jaws unlike anything that I had seen 

 before in that, instead of having teeth, 

 the margin was provided with a contin- 

 uous, highly sculptured ridge of dentine. 

 It wasn't until we found a complete set 

 of lower jaws that we properly identified 

 these scales and fragments. The jaws 

 were short, massive, and fused at the 

 symphysis. They could only belong to 

 lung-fishes, even though they lacked the 

 typical tooth plates. The surface was 

 shiny and punctate like that of the scales 

 we had referred to "crossops," and the 

 biting surface showed the peculiar, sculp- 

 tured, dentine ridges that had puzzled 

 us earlier. 



This was an exciting find because the 

 only other lungfish as old was a single 

 specimen from the Hunsriickschiefer of 

 Germany. Here we were at the begin- 

 nings of the recorded history of a group 

 that has persisted nearly 400 million 

 years to the present day. Moreover, it 

 is one of the few major groups that was 

 known from fossils before living mem- 

 bers were discovered. Lungfishes from 

 the British Old Red Sandstone were first 

 described in 1828, several years before 

 living lungfishes, Lepidosiren and Protop- 

 terus, were discovered in South America 

 and Africa. Fossil tooth plates of Cerato- 

 dus were described in 1838, while the 

 closely related living genus of Australia, 

 Neoceratodus, was not found until 1870. 

 These three living lungfishes are a small 

 remnant of a long evolutionary history. 

 They are archaid forms that might well 

 be called "living fossils," much like the 

 living coelacanths that have been caught 

 in recent years in the Indian Ocean. 



The group gets its name from the pres- 

 ence of lungs, which are known, of course, 

 only in modern forms. Like other fishes, 

 they possess gills, too, but the lungs 

 permit them to get their oxygen from 

 the air as well as from the water. This 

 is often necessary in habitats of living 

 lungfishes. Many live in tropical swamps 

 where the water may contain so little 

 oxygen that the fishes would die without 

 an additional supply. Others live in 

 bodies of water that dry up periodically, 

 and the lungs permit them to survive 

 until the next wet season, which they 

 usually do buried in the mud. Burrows 

 of fossil lungfishes are known as far back 

 as the late Paleozoic, which means that 

 habits similar to those of modern forms 

 were developed at least 250 million years 

 ago. In Upper Devonian rocks, lung- 

 fishes are associated with a peculiar ar- 

 mored fish that is known to have lungs 

 because they have been preserved as fill- 

 ings. Also associated is a crossopterygian 

 fish that may have had lungs because it 

 is close to the ancestry of land animals. 



These points suggest that lungfishes may 

 have developed this characteristic fea- 

 ture quite early in their history, but we 

 do not expect to find any clue to this 

 question in our new Lower Devonian 

 discovery. 



Last summer, after we realized that 

 there were lungfishes in our quarry, we 

 worked with added enthusiasm. When 

 we finished the field season, we had skulls, 

 plates of the cheek and gill cover, shoul- 

 der girdles, and many scales — enough 

 to fill five Museum specimen drawers. 

 Although they are not showy specimens 

 such as we would be apt to select for an 

 exhibit, they will add much to the knowl- 

 edge of the structure of early lungfishes. 



Right now the long process of prepa- 

 ration is progressing slowly. The hard 

 limestone must be removed by careful 

 grinding or chipping, and on irregular 

 surfaces where the rock adheres strongly, 

 dilute acetic acid must be used to dis- 

 solve it off. Already we can see that 

 ridged tooth plates were never devel- 

 oped in our form, so we can assume that 



Above left: A closer view of the excavation site. 



Below: A view of the Big Horn Mountains of Wyoming, looking across Cottonwood Canyon. Site of 

 the Museum expedition's excavation is encircled. 



Photographs by E, S. Richardson, Jr. 



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