The acidic, neutral, and amino sugar contents of the hydrolysates were determined by high-performance anion exchange-pulsed amperometric detection (HPAE-PAD) by using a CarboPac PA100 column (Dionex P/N043055), according to the Dionex instructions. Non-hydrolyzed samples were analyzed similarly, in order to detect free monosaccharides in the samples. The results obtained (means±standard deviations) for each species come from three analyses performed with three different pools of gastroliths. Blank experiments were performed using BSA diluted in 10% acetic acid and submitted to all the steps of the extraction procedure. It is to notice that this technique does not allow the quantification of sialic acids, which are destroyed during hydrolysis with TFA, nor the detection of iduronic acid because of the lack of available standards. All the analyses have been performed in the same lab, UPSP PROXISS, AgroSupDijon, Dijon, and by the same person to avoid possible experimental discrepancy.