A Portrait of Cristiano Dal Sasso

by Steve Brusatte

A few years ago the dinosaur world was abuzz with news of a stunning new baby dinosaur found in Italy. This dinosaur, later christened Scipionyx in a groundbreaking paper by two young Italian cientists, showed evidence of wellpreserved organ imprints, structures rarely fossilized. Today, these enigmatic organ imprints continue to spawn debate. Much of this debate has been due to the intriguing hypotheses proposed by Dr. Cristiano Dal Sasso, the lead author who described Scipionyx in 1998.

Cristiano Dal Sasso first became interested in fossils as a young child, when he marveled at the beauty of what he called \"witnesses of life history.\" However, not only paleontology, but also all natural sciences, caught his interest. In fact, when attending the University of Milan, Dal Sasso\'s first choice for a course of study was a degree in natural sciences, which to him represented a perfect medium between biological and geological studies. However, over time Dal Sasso\'s interest in fossils took over, and he eventually earned a degree that molded his interests.

With a degree in hand, Dal Sasso got a technician position in the Laboratory of Paleontology at the Museum of Natural History in Milan, where he set out to learn more about Italy\'s fossil vertebrates. The only problem, though, was the fact that at the time of his graduation no known dinosaur fossils had been found in Italy. But, as it turned out, Dal Sasso would play a major role in describing the first of what may be many dinosaurs from the boot country. At present, only three dinosaur genera are known from Italy, all of which have been described or found very recently. Because of the lack of dinosaur fossils at the time of his graduation, Dal Sasso first studied marine reptiles, which are more common in the Alpine region of Italy. \"Only later (did) I move on to the dinosaurs, my first love, but impossible to become reality in my country until the discovery of (the first Italian dinosaur),\" he said.

In his early years, before he even saw the now-famous specimen of Scipionyx, Dal Sasso described two new genera of aquatic reptiles: Besanosaurus leptorhynchus, a six meter long shastasaurid ichthyosaur from the Besano-Monte San Giorgio area, and Aphanizocnemus libanensis, a dolichosaur-like varanoid which represents the first reptile found in the Cenomanian of Lebanon. While these discoveries proved interesting to Dal Sasso, he still longed to study dinosaurs. In the early 1990\'s he was presented with an opportunity that would change his life.

In 1980, in the Matese mountains of Benevento Province (about 50 miles northeast of Naples), amateur paleontologist and fossil collector Giovanni Todesco discovered a rather unusual reptile in the Early Cretaceous marine outcrops of Pietraroia. The Pietraroia area had been well known for its exquisite fish, shrimp, and crocodilian remains, but Todesco\'s discovery was like nothing he had ever seen. However, only thinking that it was a strange reptile or bird, Todesco literally forgot about the fossil until 1993, when, upon watching the movie Jurassic Park, he showed the specimen to professional paleontologist Dr. Giorgio Teruzzi, Curator of Paleontology at the Museum of Milan.

Teruzzi was amazed: Todesco\'s specimen was the first known Italian dinosaur. After identifying the specimen, Teruzzi presented Dal Sasso with the opportunity to study the fossil. In the autumn of 1993 Dal Sasso began the task of examining the animal, a process which would not culminate for another five years. Before Dal Sasso even had a chance to properly examine it, however, the dinosaur that would later be named Scipionyx was first presented in a brief note authored by G. Leonardi and Teruzzi. After the publications of this preliminary paper, Dal Sasso joined forces with Marco Signore, a student at the University of Naples, to further study the specimen.

Around the time Signore joined the team, Dal Sasso was given permission by Superintendency of Salerno, where the fossil was housed, to prepare the specimen. Thanks to his skills in mechanical preparation of fossils preserved in limestone, Dal Sasso finished a beautiful preparation of the dinosaur in three years, a long period for a tiny fossil.

However, during the time of preparation tragedy struck. Dal Sasso was involved in a very serious car accident, which resulted in the amputation of his right leg and nearly the loss of his life. During the ordeal Dal Sasso was unsure whether he would still have the chance to prepare and study the specimen after he recuperated. Luckily, for science, Dal Sasso was allowed to work on the specimen after his accident. Between 1994-1997, along with preparator Sergio Rampinelli, Dal Sasso meticulously removed matrix and dirt from the dinosaur specimen, revealing its extraordinary preservation of soft tissues. One year after preparation was completed, Dal Sasso and Signore officially named Scipionyx in a 1998 paper appearing in Nature. Dal Sasso and Signore\'s 1998 paper revealed information that was hitherto unheard of: amazing soft tissue anatomy in a dinosaur.

Among other soft tissues, horny sheaths on the ungual phalanges, muscle remains in the pectoral and proximo-caudal regions, tendons under the tail, connective tissues associated with muscle bundles, trachea rings close to the furcula, and the entire intestine are preserved. In addition, there are traces of what might have been the liver, preserved as a reddish halo made of hematite. And, to make matters better, all preserved soft parts, save for the intestine and supposed liver, are 3-D mineralized tissues, and not simply
imprints.

While the presence of the liver still causes debate, the mere suggestion of this organ has caused the most controversy of any of the soft tissue remains. Physiologist John Ruben and a group of coauthors described the supposed liver in depth, arguing that the liver \"proved\" that Scipionyx had a crocodile-like metabolism, and, therefore, was likely not warm-blooded and related to birds. This hypothesis was based on Ruben\'s interpretation of Scipionyx\'s lungs, which he believed were powered by a liver-piston system. Dal Sasso himself is still unclear if a liver is even preserved, much less about its function. \"I am not a physiologist.

However, from a morphological point of view, in my opinion there is not definite evidence that the liver of Scipionyx, despite (being) unusually deep under UV light, was powered by diaphragmatic muscles and was then eventually capable to act as a piston,\" he said.

However, Dal Sasso did say that, \"there are so many synapomorpies supporting the dinosaur-bird link that any alternative hypothesis on bird evolution seems to me definitely less parsimonious and, frankly, unlikely.\" Opposing Ruben have been several other researchers, whom have tried to use Scipionyx\'s short gut as an implication of high metabolism. Dal Sasso also is cautious when discussing this viewpoint, saying that, \"a short gut does not necessarily mean high metabolism, but rather indicates a high absorption rate. At least in living tetrapods, the anatomy of the digestive system depends primarily on their diet: meat-eating animals have a shorter intestine than vegetarian ones, which is independent from their thermal behavior.\"

So, where does this leave Dal Sasso? In addition to supporting the dinosaurbird link, he believes that during the reign of the dinosaurs, some dinosaurs may have had time to develop a variety of metabolic strategies, reaching diverse physiological adaptations as varied as their shapes and sizes. These adaptations, according to Dal Sasso, may have ranged from the low metabolic levels of gigantothermy in larger animals to a higher-level warm-blooded-like metabolism in theropods, Scipionyx included.

While he believes that Scipionyx may have been warm-blooded, Dal Sasso believes that this warm-bloodedness likely varied from what we called endothermy today. In a paper published with John Ruben and several of his students, Dal Sasso argued that theropods may have used a pattern of exercise physiology unlike that of any group of living tetrapod. According to this model, Dal Sasso said, most theropods had low metabolic rates, like cold-blooded animals, while at rest. However, the supposed presence of the diaphragm-assisted lung ventilation, powered by the aforementioned controversial liver-piston pump, might have allowed certain theropods to enhance their pulmonary exchange rates when necessary. While this hypothesis is still controversial, Dal Sasso believes that it represents the most likely condition in Scipionyx and other theropods.

Now that Scipionyx has been named and briefly studied, Dal Sasso said that a more complete description of its remains are in progress. In addition, scientists are still waiting to hear where the specimen will be finally housed. Currently the fossil is on exhibit at the Rocca dei Rettori in the town of Benevento, not far from where it was discovered. In the city of Pietraroia, funds are available, according to Dal Sasso, from the Italian Ministry of Culture to convert a retirement home into a fossil museum. Whether this project will come to fruition depends on \"politics,\" but in the meantime new excavations are going near the Scipionyx site, led by the Museum of Milan.

Until the specimen is finally permanently exhibited and exhaustively described, there will still be speculation on its proper phylogenetic position. Scipionyx shows an enigmatic mosaic of characters which does not allow an attribution to any known coelurosaurian family. Without doubt, however, Dal Sasso believes Scipionyx to be a Maniraptoriform, because it shares with the clade at least six unambiguous synapomorphies. But, Scipionyx also differs from other maniraptors in the unique possession of an posteriorly elongate dentary, the compressed nature of its radiale and semilunate carpal, and in its primitive retention of a stout lachrymal, large prefrontal, and pronounced scapular acromion.

According to Dal Sasso, these characters may mean that Scipionyx represents a transitional clade between Compsognathus-Sinosauropteryx and the primitive Maniraptoriformes. While Scipionyx has occupied the majority of Dal Sasso\'s professional life, he has also been in the news recently for the discovery of a new early Jurassic theropod that may give new insights into the evolution of the tetanurans. Nicknamed \"Saltriosaur,\" this specimen is awaiting description and publication. This strange theropod comes from a Sinemurian rock unit located near the town of Saltrio, north of Milan and near the Swiss border. The specimen, discovered in 1996, includes less than 100 individual bones (likely about 10 percent of the complete skeleton). Judging by the fragments, Dal Sasso believes the theropod was likely near 26 feet long, and probably weighed over a ton. One tooth, measuring 2.8 inches, was also found.

Dal Sasso believes the specimen to be important because it comes from \"ancient\" rocks, formed during a time when it was thought that only primitive ceratosaurs made up the world\'s theropod fauna. The Saltriosaur, however, preserves an interesting framework different from the anatomy of such ceratosaurs and contains anatomical features typical of more derived theropods: members of the tetanuran lineage. \"The Saltriosaur discovery is crucial for the knowledge of carnivorous dinosaur evolution because it (might) represent the most ancient large tetanuran in the world,\" Dal Sasso said.

University of Maryland paleontologist and theropod expert Dr. Thomas Holtz agreed, saying that, \"the specimen will be helpful in terms of the reconstruction of the dinosaurs\' history and interrelationships between various groups.\" Dal Sasso also pointed out that the discovery of the specimen helps debunk the notion that Italy was made up of a series of small islands during the early Jurassic.

While the Saltriosaur is a very important specimen, it has not yet been properly described, figured, or even named. Dal Sasso is currently working on a scientific description of the animal, which may be published in 2002. Until the publication of that paper, Dal Sasso will continue his work at a quarry in Besano, where hundreds of Middle Triassic fishes and reptiles are emerging. In addition, he plans on continuing his fledgling studies on mosasauroids of Lebanon. According to Dal Sasso, a new dolichosaur taxon will soon be described.

Perhaps Dal Sasso\'s most impressive ongoing project is the completion of his book \"Dinosauri italiani.\" Published in December of 2001, this book is the first popular volume on Italy\'s dinosaurs, and includes information on all Italian dinosaur footprint sites, along with data on the three Italian dinosaur taxa (Scipionyx, the Saltriosaur, and a hadrosaur known as \"Antonio\" found near Trieste and currently under study). \"This kind of book is very innovative here because all popular texts on dinosaurs in the Italian language are simple translations from English or deal with dinosaurs from around the world. Moreover, except for a recent by already outdated volume on Jurassic footprints from Rovereto, this is the first unique comprehensive book on Italian dinosaurs,\" Dal Sasso said.

Upon publication of the book, he hopes to find an English editor. Based on his groundbreaking studies of Italian dinosaurs, if Dal Sasso\'s writing matches his flair for discovery, then his book should be a smash hit.

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