Egg preservation in an Eocene stingray (Myliobatiformes, Dasyatidae) from Italy
Bibliographic record
Abstract
Known since the 16th century, Pesciara di Bolca in Italy represents one of the most intensively sampled Eocene marine localities, providing an unparalleled window on the early evolution of modern marine faunas (Friedman and Carnevale, 2018). Although the long-term collecting efforts have resulted in the identification of more than 80 vertebrate families, the complex alpha taxonomy of chondrichthyans, mostly represented by exquisitely preserved individuals, has received attention only in the last few years (Fanti et al., 2016; Marramà et al., 2017, 2018a, 2018b, 2018c, 2018d). Restoration of damage caused by an earthquake brought the historical Bolca collection of the Museo Geologico Giovanni Capellini (Bologna, Italy) under close reexamination. Among others, a complete whiptail stingray of the myliobatiform family Dasyatidae, Tethytrygon muricatus, was restored and examined in detail. The use of ultraviolet (UV) light unveiled details of the shape and size of the fins, individual skeletal cartilages, and soft tissues. The individual is interpreted as a sexually mature female based on the absence of claspers and presence of the uterus bearing four eggs. This is the first report of preserved fossilized eggs for stingrays, and in general of eggs in situ in a fossil batoid. Shape, microscopic structure, and relative size of the eggs compared with the overall body size of the specimen indicate an early stage of development of the eggs but also provide a remarkable opportunity to compare fossil and extant representatives of this clade and to further discuss the postulated Eocene ‘nursery’ habitat for the Bolca locality. This fossil demonstrates that a modern reproductive strategy had already been acquired in the early Cenozoic at a body size similar to that of sexually mature extant stingrays.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".