Meet Old Crusty, a skull and mandible of an extinct lemur that was extracted from a "rock" - a "breccia" on the floor of Anjohibe Cave in northwestern Madagascar!
Left: Painted cast of Old Crusty in its original matrix. Right: Old Crusty, emancipated, but shown in its original position in the stone. (Photograph by Marina Blanco, 2006).
“Old Crusty” ( Archaeolemur sp. cfa. edwardsi ) was discovered on August 10, 1996 by Trevor Worthy, one of the world's experts on large, flightless birds. In 1996, he was in the land of elephant birds – Madagascar – accompanying David Burney's mission to Anjohibe Cave in the northwest. The skull was entirely embedded in cave matrix, and hidden behind some spectacular cave formations called speleothems . Anjohibe is one of the caves of Andranoboka – a series of cave systems 73 km northwest of Madagascar's second largest city, Mahajanga, and not far from the village of Mitsinjo. Anjohibe (literally, Big Cave ) is the southeastern system ; it has 13 entrances and numerous passageways, marvelous pools, and beautiful stalactites and stalagmites.
Pool inside Anjohibe Cave (Photograph by Karen Samonds)
The smaller cave system is called Anjohikely (literally, Small Cave ), located only several kilometers away from the big cave. It has fewer but no less magnificent formations.
Portal into the past: One of the entrances to the Anjohikely Cave System. (Photograph by David A. Burney, 2004)
Also on that 1996 expedition to Anjohibe was an assortment of scientists and explorers, including anatomist and fossil primate specialist William Jungers (Stony Brook, Department of Anatomical Sciences) and science writer Peter Tyson. Tyson described Trevor Worthy and his discovery of Old Crusty in his book, T he Eighth Continent: Life, Death and Discovery in the Lost World of Madagascar . Trevor Worthy was a "man's man" – an experienced Aussie fieldworker, very direct, independent and sure of himself. He loved to venture off, away from the crowd of scientists and students, to explore the cave's nooks and crannies all by himself. One day he found himself between the speleothems in a remote corner of the big cave barely big enough to fit his frame, and he saw the eye sockets of Old Crusty staring right back at him, but frozen in stone on the floor of the cave.
The skull and mandible of Old Crusty could not be dug out of the rock that imprisoned them – not easily at least, and certainly not while in the cave; the matrix was hard and solid. Instead an entire block of cave matrix, with Old Crusty in it, had to be chiseled out of the floor and carefully packed. That block made its way first to Stony Brook University , and eventually to the University of Massachusetts , the academic home of Laurie Godfrey, a specialist on the extinct lemurs of Madagascar and especially the archaeolemurids (the family of extinct lemurs to which Old Crusty belongs). But before the skull and mandible could be studied by Godfrey, the matrix had to be removed. Before doing this laborious job, we wanted to get a rough idea of what might be inside – how complete was the skull? What could we learn about its internal structures? A series of CAT scans (Computerized Axial Tomography) would do the trick. Under the guidance of Bill Jungers, Justin Sipla (a graduate student in Anatomical Sciences at Stony Brook) did the CT scanning and digital reconstruction; his digital "dissection" of the mandible proved that the skull and mandible were virtually complete.
A CAT-scanned “slice” through the skull of Old Crusty. This non-destructive technology allows one to “see” and thus reconstruct the insides of a fossil.
Old Crusty in matrix and with upside-down mandible digitally isolated. Reconstruction by Justin Sipla, Stony Brook University, Department of Anatomy.
Then Godfrey and Jungers asked Joe Groenke, Molding and Casting Technician in the Stony Brook Vertebrate Fossil Prep Lab, to make a mold and several casts of the specimen embedded in its matrix, including one for display at the museum of the Académie Malgache in Antananarivo , Madagascar . Stony Brook illustrator Luci Betti-Nash painted the casts to match the original specimen.
Cast of Old Crusty, ready to be painted.
Now it was up to Virginia Heisey, expert preparator at the same Vertebrate Fossil Prep Lab, to clean the matrix off the skull and mandible. This was a job that required tremendous skill and careful attention lest the fossil crumble into a thousand pieces. In fact pieces did require gluing as they emerged, but the results were outstanding. And the skull and mandible were freed at last.
Old Crusty with cave breccia matrix removed; University of Massachusetts Department of Anthropology.
But there were other surprises to be had – among them a partial orbit and frontal of a young pygmy hippopotamus – buried under the skull.
The eye socket of Madagascar 's pygmy hippo.
Virginia noticed that the matrix contained microfaunal remains, and mentioned this to then Stony Brook graduate student and former U. Mass undergraduate, Karen Samonds. Karen was working on her doctoral dissertation on the living and fossil bats of Madagascar , so it was no wonder that she was eager to embrace the tedious job of extracting the tiniest bits of bone and teeth from the kilogram of Crusty matrix that normally would have been, simply, discarded.
Karen Samonds collecting subfossil bat bones on the floor of Anjohibe cave.
Karen brought that project with her to Mt Holyoke College in South Hadley , Massachusetts , where she enlisted the help of an enthusiastic undergraduate student, Sara Parent (class of 2005). Together, Sara and Karen identified over 60 microfaunal remains of endemic bats, carnivores, and rodents, including Eliurus sp . (Rodentia) , Hipposideros cf. commersoni and Triaenops sp. (Chiroptera) , and Galidia cf. elegans (Carnivora). Sara sent the following text on her favorite specimens:
CRUSTY MICROMAMMALS ON THE HEADS OF PINS
The matrix contained some teeth of tiny endemic rodents belonging to the genus Eliurus, the Malagasy tuft-tailed rat. In fact, the only identifiable subfossil materials recovered from these tiny rodents were a few extremely small molars. Some were smaller than the pin heads I used in mounting them. Due to their small size, one cannot detect their very interesting morphology without the aid of a microscope. Once they were placed under the scope, however, I could see characteristics that are unmistakably diagnostic of the genus Eliurus.
Lateral and occlusal view of M 3 of Eliurus myoxinus , the Malagasy tuft-tailed rat, extracted from the matrix surrounding Old Crusty. (Actual size approximately 2 mm)
Also extracted from Old Crusty's matrix were the minuscule skulls and jaws of bats. Karen, the bat specialist, got her just reward for a lot of hard work! Shown here, on the top, are the skull and jaw of a variant of Commerson's leaf-nosed bat, Hipposideros commersoni . Below these is the lower jaw of Triaenops sp., the triple nose-leaf bat. To extract these fossils, a weak solution of acetic acid was used to dissolve the limey matrix.