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Heartless? The fossil dinosaur's ‘heart’ (centre) may actually be a mineral concretion. Credit: AP

This spring, a team led by researchers from North Carolina State University received widespread publicity for their claim to have discovered the remains of a heart within the ribcage of a 66-million-year-old dinosaur specimen.

But since then doubts have been growing about whether the discovery is all that it seemed. Palaeontologists from the University of Texas are now preparing a rebuttal that is expected to say that the fossil — from a herbivorous Thescelosaurus — is a deposition of minerals known to geologists as a concretion.

Nature has also learned that one of the original article's authors — a commercial fossil hunter who found the specimen in South Dakota — has, according to federal records, been convicted of trafficking in Native American artefacts stolen from federal lands.

Although there is no evidence of any wrong-doing in the current case, and no one is making any such claims, the fact that the researchers were unaware of this background has again raised the question of how thoroughly institutions investigate the provenance of the material they collect.

The heart was described as having four chambers and a single systemic aorta, more like a human heart than that of a reptile, which has only three chambers and paired systemic aortas. This suggested to the authors “the existence of intermediate-to-high metabolic rates among dinosaurs”, strengthening the hypothesis that many were warm-blooded (see Science 288, 503–505; 2000).

But immediately after the article was published, some top US palaeontologists questioned its claims. The team at North Carolina State University — including lead author Paul Fisher and senior curator of palaeontology Dale Russell — then put up computerized tomography (CT) scan photos of the specimen on the museum's website.

Last month, says Russell, the specimen was inspected by palaeontologist Timothy Rowe, an authority on CT scans and director of the Vertebrate Paleontology Laboratory at the University of Texas, the only facility with a CT scanner dedicated to such studies.

Working with University of Texas geologist Earle McBride, an authority on palaeontological concretions, Rowe is preparing the rebuttal for Science . Rowe — reportedly the only external palaeontologist to see the specimen since it was described — declines to discuss the details of his report before submission and publication.

But Russell says that, after visiting the museum, Rowe “doesn't think it is a heart”. “We have no fear,” adds Russell. “We will follow the truth. We have no case but to find out what it is. I look at it as an adventure.”

North Carolina officials say they were unaware of the court record of Michael Hammer, the fossil hunter who provided the specimen. Hammer, who runs Hammer and Hammer Paleotek, a palaeontology preparation company near Jacksonville, Oregon, has refused several requests for an interview.

Officials from the North Carolina Museum of Natural Sciences in Raleigh — where the heart specimen is displayed in a $70 million facility opened last April — maintain that their enquiries when they bought the fossil in 1996 were sufficient to document that the sale was legitimate.

Russell says he had known Hammer for more than five years before that, and that Hammer invited him to the fossil and mineral show in Tucson, Arizona, in about 1995 to see the Thescelosaurus heart, which he was trying to sell. Hammer has said he found the fossil in 1993 in the Hell Creek formation on private land in northwest South Dakota.

Using funds raised by a support group, the North Carolina museum paid Hammer $350,000 for the Thescelosaurus. When told that federal records showed that Hammer pleaded guilty in September 1994 to two charges of trafficking in artefacts stolen from federal land in Utah, Russell said he was unaware of this.

In 1990, when federal and state authorities raided Hammer's home, records show they found Native American human remains, which were repatriated to a Californian tribe in 1996. Through his wife, Hammer has denied any impropriety over the Thescelosaurus specimen. She attributes the earlier prosecutions to overly aggressive law enforcement in an area of changing, confusing legislation.

Earlier this month, North Carolina palaeontologists took CT scans of the heart specimen at the university's veterinarian college. Museum officials say they are clearer and more helpful than the original scans. But some palaeontology authorities say no conclusion can be drawn until the remnant is cut open.

→ http://www.dinoheart.org