Czatkowiella: the terror of mixed up puzzle pieces

Fissure fossils
are wonderful in that they are typically uncrushed and readily extracted. They are also horrible in that many bones are fragments, few are attached to each other and worst of all…several sizes, species and genera can get mixed up together. That’s the case with Czatkowiella harae (Fig. 1).

Here’s how Borsuk−Biaynicka and Evans 2009 described the scenario:
“The description that follows is based on isolated and fragmentary bones extracted from a microvertebrate−bearing deposit containing the remains of at least four other small reptiles. Of these, Czatkowiella is overlapped by the archosauriform Osmolskina (Borsuk−Białynicka and Evans 2003) in the upper end of its size range, by Pamelina (Evans 2009) in the middle part of its range, and by Sophineta (Evans and Borsuk− Bialynicka 2009b) at the extreme lower end. This presents something of a challenge in terms of attributing elements, particularly with Osmolskina which is the more closely related taxon. For the smaller diapsids, we have used a combination of fit for individual elements and the general rule that if a bone of the same morphology occurs through a wide size range it is more likely to be Czatkowiella, since there is little variation in jaw size for the two small lepidosauromorphs. The structure of the dentition (using scanning electron microscopy) permits association of tooth−bearing elements, the maxilla then forming a template around which to fit other skull bones.”

Figure 1. Czatkowiella harae bits and pieces here reconstructed as best as possible. Note the size difference here between the large maxilla and the small one.

Figure 1. Czatkowiella harae bits and pieces here reconstructed as best as possible. Note the size difference here between the large maxilla and the small one.

Czatkowiella harae 
(Borsuk−Biaynicka & Evans 2009) Early Triassic ~250 mya, was recently described as a long-necked sister to Protorosaurus Here it nests between Ixalerpeton and Malerisaurus, two taxa that were not tested originally. Several sizes are known, all from disarticulated bone fragments. The number of cervicals is unknown but sister taxa have 8. Hopefully all of the bones assigned to this genus actually belong to this genus.

Figure 2. Borsuk−Biaynicka and Evans tested only Prolacerta and Protorosaurus among the Protorosauria.

Figure 2. Borsuk−Biaynicka and Evans tested only Prolacerta and Protorosaurus among the Protorosauria.

Distinct from Protorosaurus,
the skull of Czatkowiella was longer, lower, flatter and wider. The maxilla ascended in a process just aft of the long naris. The jugal had a stub quadratojugal process. The descending process of the squamosal was gracile and acute. The upper temporal fenestra was smaller. The lateral processes of the parietal were more posteriorly oriented. The cervicals and dorsals were shallower with lower neural spines.

If the two maxillae are indeed conspecific, then the shape of the maxilla changes with ontogeny.

The Borsuk−Biaynicka and Evans cladogram 
suffers from massive taxon exclusion as it nests

  1. Lepidosauromorpha  is wrongly nested as a sister clade to Protorosaurus + Czatkowiella and the rest of the taxa listed below.
  2. The gliderCoelurosaurus, is wrongly nested as a sister clade to Protorosaurus and the rest of the taxa listed below.
  3. Coelurosauravus, is wrongly nested as a sister clade to Ichthyosauria + Thalalattosauria and the rest of the taxa listed below.
  4. Ichthyosauria + Thalalattosauria is wrongly nested as a sister clade to Choristoderes + Turtles  but it is a sister to the clade Sauropterygia.
  5. Choristodera is wrongly nested as a sister clade to Tanystropheus, Macrocnemus, Prolacerta and the rest of the taxa listed below.
  6. Prolacerta is wrongly nested as a sister clade to Trilophosaurus + Rhynchosauria but it is correctly nested as a sister to the Archosauriformes.

Still not sure
how Prolacerta and Protorosaurus get separated in cladograms produced by PhDs.

Borsuk−Biaynicka & Evans 2009 were using outdated taxon sets,
but then, these preceded the publication of the large reptile tree by a few years.

Quick reminder,
Tritosaurs, including Tanystropheus and Macrocnemus are not related to protorosaurs in the large reptile tree despite the many convergent traits.

References
Borsuk−Biaynicka M and Evans S E 2009. A long−necked archosauromorph from the Early Triassic of Poland. Paleontologica Polonica 65: 203–234.

wiki/Czatkowiella

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