Pterodactylus antiquus extreme closeups: Tischlinger 2020

Paleo-photographer Helmut Tischlinger 2020
brings us extreme closeups of the first pterosaur ever described, Pterodactylus antiquus (Figs 1–7), in white and UV light. Here both photos of the same area are layered precisely to demonstrate the different details each type of light brings out.

The text is German.
The abstract and photo captions are duplicated in English.

Pterodactylus antiquus (Collini 1784, Cuvier 1801, 1809, Sömmerring 1812, BSP Nr. AS I 739No. 4 of Wellnhofer 1970; Late Jurassic) was the first pterosaur to be described and named.

Figure 1. Reconstruction of Pterodactylus antiquus made prior to Tischlinger 2020.

Figure 1. Reconstruction of Pterodactylus antiquus made prior to Tischlinger 2020.

From the Abstract:
“On the occasion of the reopening of the Jura Museum Eichstätt on January 9, 2020, the Bavarian State Collection for Paleontology and Geology, Munich, provided the Jura Museum with one of its most valuable fossil treasures as a temporary loan. The “Collini specimen”, first described in 1784, is the first scientifically examined and published fossil of a pterosaur and has been at the center of interest of many natural scientists since it became known… An examination of the texture of the surface of the limestone slab and the dendrites on it suggests that it does not come from Eichstätt, as has been claimed by Collini, but most likely from the Zandt-Breitenhill quarry area about 30 km east of Eichstätt. For the first time, a detailed investigation and pictorial documentation were carried out under ultraviolet light, which on the one hand document the excellent preservation of the fossil, and on the other hand show that there has obviously been no damage or manipulation to this icon of pterosaurology during the past almost 240 years.”

Figure 2. Pterodactylus wing ungual.

Figure 2. Pterodactylus wing ungual in white light and UV. Not sure why the two images are not identical, but elsewhere teeth appear and disappear depending on the type of light used.

The wing tip ungual 
appears to be present in visible light, but changes to a blob under UV (Fig. 2). Other pterosaurs likewise retain an often overlooked wingtip ungual.

In the same image
the skin surrounding an oval secondary naris within the anterior antorbital fenestra appears. Otherwise very little soft tissues is preserved.

The ‘secondary naris’ may be a new concept for some,
so it is explained below. This is not the same concept as the hypothetical ‘confluent naris + antorbital fenestra’ you may have heard about. Remember, ‘pterodactloid’-grade pterosaurs arose 4x by convergence. So each had their own evolutionary path.

Figure 3. Pterodactylus rostrum from Tischlinger 2020, colors added here. Note the original naris appears as a vestige above the maxilla tip, as in the Triassic pterosaur, Bergamodactylus and the Pterodactylus ancestor, Scaphoganthus.

Figure 3. Pterodactylus rostrum from Tischlinger 2020, colors added here. Note the original naris appears as a vestige above the maxilla tip, as in the Triassic pterosaur, Bergamodactylus and the Pterodactylus ancestor, Scaphoganthus. The shape of that narial opening is different in UV and white light.

The elements of the paper-thin rostrum
are colorized here (Fig. 3). There are subtle differences between the white light and UV images. The pink color represents a portion of the nasal that extends to the anterior maxilla and naris as in other pterosaurs and tetrapods. Did I just say naris? Yes.

Note the original naris here appears as a vestige
in its usual place above the maxilla tip, as in the Triassic pterosaur, Bergamodactylus and the late-surviving Pterodactylus ancestor, Scaphoganthus. The transition to this vestigial naris is documented in the rarely published n9 (SoS 4593), n31 (SoS 4006) and SMNS 81775 tiny transitional taxa (Fig. 4). After testing, all these turn out to be miniaturized adults traditionally mistakenly considered to be juveniles, only by those pterosaur workers who have excluded these taxa from phylogenetic analysis.

Figure 2. Click to enlarge. Painten pterosaur compared to phylogenetic sister taxa. Ornithocephalus and SMNS 81775 are the basal taxa here. Note that while everything else grows on derived taxa, the metacarpus stays the same size. The large size of the Painten pterosaur, along with the greater length of pedal digit 3 and the brevity of the metacarpus sets it apart in its own clade, of which this the first known representative. Larger than its relatives, this is an unlikely juvenile (contra Hone, see below).

Figure 4. Click to enlarge. Painten pterosaur compared to phylogenetic sister taxa. Ornithocephalus and SMNS 81775 are the basal taxa here. Note that while everything else grows on derived taxa, the metacarpus stays the same size. The large size of the Painten pterosaur, along with the greater length of pedal digit 3 and the brevity of the metacarpus sets it apart in its own clade, of which this the first known representative. Larger than its relatives, this is an unlikely juvenile (contra Hone, see below).

That’s why it is so important
to include all pterosaurs specimens as taxa in analysis. Otherwise you will miss the phylogenetic miniaturization that occurs at the genesis of major clades, the phylogenetic variation within a genus, and the evolution of new traits that have been overlooked by all other pterosaur workers.

Figure 2. Pterodactylus metacarpus including 5 digits.

Figure 5. Pterodactylus metacarpus including 5 digits. Colors added here.

The elements of the right metacarpus
are better understood and communicated when colorized (Fig. 4). Not sure where the counter plate is, but it may include some of the elements missing here, like the distal mc1. The left manus digit 5 is on that counter plate, judging from the broken bone left behind on the plate.

Figure 6. Pterodactylus antiquus pes in situ and restored to in vivo appearance.

Figure 6. Pterodactylus antiquus pes in situ and restored to in vivo appearance.

The pes is well preserved
Adding DGS colors to the elements helps one shift them back to their invivo positions. The addition of PILs (parallel interphalangeal lines, Peters 2000) complete the restoration. This is a plantigrade pes, judging by the continuous PILs that other workers continue to ignore.

Figure 6. Pterodactylus in situ under white light and UV from Tischlinger 2020. Colors added here.

Figure 7. Pterodactylus in situ under white light and UV from Tischlinger 2020. Colors added here.

Sometimes PhDs overlook certain details.
And that’s okay. Others will always come along afterward to build on their earlier observations. Tischlinger 2020 provides that excellent opportunity.


References
Collini CA 1784. Sur quelques Zoolithes du Cabinet d’Histoire naturelle de S. A. S. E. Palatine & de Bavière, à Mannheim. Acta Theodoro-Palatinae Mannheim 5 Pars Physica, 58–103.
Cuvier G 1801. [Reptile volant]. In: Extrait d’un ouvrage sur les espèces de quadrupèdes dont on a trouvé les ossemens dans l’intérieur de la terre. Journal de Physique, de Chimie et d’Histoire Naturelle 52: 253–267.
Cuvier G 1809. Mémoire sur le squelette fossile d’un reptile volant des environs d’Aichstedt, que quelques naturalistes ont pris pour un oiseau, et dont nous formons un genre de Sauriens, sous le nom de Petro-Dactyle. Annales du Muséum national d’Histoire Naturelle, Paris 13: 424–437.
Peters D 2000. Description and Interpretation of Interphalangeal Lines in Tetrapods. Ichnos, 7: 11-41
Tischlinger H 2020. Der „Collini-Pterodactylus“ – eine Ikone der Flugsaurier-Forschung Archaeopteryx 36: 16–31; Eichstätt 2020.
von Soemmering ST 1812. Über einen Ornithocephalus. Denkschriften der Akademie der Wissenschaften München, Mathematischen-physikalischen Classe 3: 89-158.
Wellnhofer P 1970. Die Pterodactyloidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Abhandlungen der Bayerischen Akademie der Wissenschaften, N.F., Munich 141: 1-133.

wiki/Pterodactylus

 

 

 

 

The snakebird lacks external nares, breathes through its mouth

Figure 1. Skull of Anhinga rufa, an Old World relative of the New World Anhinga anhinga. Note the expansion of the maxilla (or overlying horny tissue) nearly obscuring the naris and antorbital fenestra. Compare to the loon in figure 3.

Figure 1. Skull of Anhinga rufa, an Old World relative of the New World Anhinga anhinga. Note the expansion of the maxilla (or overlying horny tissue) nearly obscuring the naris and antorbital fenestra. Compare to the loon in figure 2.

Anhinga anhinga (Linneaus 1766; 89cm) is the extant snakebird, which swims underwater and stabs its fish prey with its sharp beak, striking like a snake. It breathes only through the mouth as the bones and other hard tissues around the nostrils are overgrown. The feathers do not shed water, so some time is spent drying the feathers prior to flying. Snakebirds are related to grebes (genus: Aechmophorus) and loons (genus: Gavia, Fig. 2).

Figure 2. Skull of the common loon (Gavia stellata) showing the primitive state, with large external nares and antorbital fenestra.

Figure 2. Skull of the common loon (Gavia stellata) showing the primitive state, with large external nares and antorbital fenestra.

The large number and length of cervical vertebrae
in snakebirds (Fig. 3) is more or less matched only by flamingoes (genus: Phoenicopterus) by convergence.

Figure 3. Anhinga anhinga skeleton. Note the large number of cervical vertebrae. These enable the snake-like darting of the sharp skull while attacking prey underwater.

Figure 3. Anhinga anhinga skeleton. Note the large number of cervical vertebrae. These enable the snake-like darting of the sharp skull while attacking prey underwater.

Hackett et al. 2008 nested loons with penguins.
While close, the large reptile tree (LRT, 1562 taxa) nests loons + grebes derived from terns (genus: Thalasseus) and sisters to kingfishers (genus: Megaceryle) + jabirus (genus: Jabiru) and murres (genus: Uria) + penguins (genus: Aptenodytes). Among these taxa, only Jabiru experiences a reversal in having such long, stork-like legs, a primitive trait for extant birds.

Figure 1. The rostrum of Spinosaurus. Note the maxilla rising to close off the elongate naris into a reduced anterior and posterior opening.

Figure 4. The rostrum of Spinosaurus. Note the maxilla rising to close off the elongate naris into a reduced anterior and posterior opening.

Footnote:
Another aquatic dinosaur taxon that expanded its maxilla to shut off its nostrils was Spinosaurus (Fig. 4) as we learned earlier here.


References
Hackett S et al. 2008. A phylogenetic study of birds reveals their evolutionary history. Science 320:1763–1768.
Kennedy M et al. 2019. Sorting out the Snakebirds: The species status, phylogeny, and biogeography of the Darters (Aves: Anhingidae). Journal of Zoological Systematics and Evolutionary Research (advance online publication)
doi: https://doi.org/10.1111/jzs.12299 https://onlinelibrary.wiley.com/doi/10.1111/jzs.12299

The genesis of external and internal nostrils

The origin of choanae
(internal nostrils) from the primitive dual external naris of basal vertebrates was ‘settled’ over a decade ago with the observation that Kennichthys (Fig. 1; Zhu and Ahlberg 2004; Janvier 2004) had a naris/choana at the rim of its jaws. At the time, Kennichthys was thought to be an osteolepiform and basal to tetrapods. In other words, that was the phylogenetic context at the time.

Figure 1. From Janvier 2015, evolution of the internal naris (choana) from primitive dual external nares.

Figure 1. From Janvier 2004, evolution of the internal naris (choana) from primitive dual external nares. No bony ray fin fish, sharks and placoderms are shown here, distinct from the LRT in figure 2.

However, a novel phylogenetic context
arises by greater taxon inclusion in the large reptile tree (LRT, 1548 taxa; Fig. 2).

Figure 2. Subset of the LRT focusing on basal vertebrates. Colors indicate various naris configurations. Some palates are not known.

Figure 2. Subset of the LRT focusing on basal vertebrates. Colors indicate various naris configurations. Some palates are not known.

The LRT indicates
that Kennichthys was a terminal taxon, not leading to higher taxa. Polypterus and Powichthys have/had a single external and internal naris. This pattern leads by homology to tetrapods and osteolepiforms. A reversal took place with a traditional osteolpiform, Onychodus (Fig. 3), which has dual external nares, like ray fin fish, AND an internal naris. Thereafter the internal naris disappears and dual external nares are retained.

FIgure 1. Several views of the Onychodus skull.

FIgure3. Several views of the Onychodus skull. Note the twin external nares AND the internal naris. 

Lungfish have/had two internal nares.
Some higher, predatory placoderms have a single external naris (not sure about the palate). A clade including living lizardfish (Trachinocephalus), Cheirolepis, and spiny sharks by convergence seem to have one external naris (not sure about the palate).


References
Chang M and Zhu M 1993. A new Middle Devonian osteolepidid from Qujing, Yunnan. Mem. Assoc. Australas. Palaeontol. 15 183-198.
Janvier P 2004. Wandering nostrils. Nature 432:23–24.
Zhu M and Ahlberg P 2004. The origin of the internal nostril of tetrapods. Nature 432:94-97.

wki/Stensioella
wiki/Kenichthys

The near closure of the naris in Spinosaurus

Short note on a long rostrum today:

Figure 1. The rostrum of Spinosaurus. Note the maxilla rising to close off the elongate naris into a reduced anterior and posterior opening.

Figure 1. The rostrum of Spinosaurus MSNM V4047. Note the maxilla rising to close off the elongate naris into a reduced anterior and posterior opening. SF = sub-narial foramen. 

I just found this fascinating.
The naris of Spinosaurus (Stromer 1915; Cretaceous; MSNM V4047) was overlaid by the maxilla sealing off most of what had been the elongate opening (Fig. 1).  I suppose that supports a semi-aquatic niche and reduced olfactory input. As others have noted, the rostrum has sensory pits, perhaps, as in crocodilians, for underwater vibration sensing.

Figure 2. Diagram from Dal Sasso et al. 2005, colors and overlay added to show  dorsal expansion of the maxilla to cover an elongate naris.

Figure 2. Diagram from Dal Sasso et al. 2005, colors and overlay added to show dorsal expansion of the maxilla to cover an elongate naris.

Dal Sasso et al. 2005 wrote:
“The external naris is retracted farther caudally on the snout than in other spinosaurids and is bordered exclusively by the maxilla and nasal.” The authors identified the anterior naris as a ‘sub-narial foramen’. The naris continues to contact the premaxilla in all related taxa (Fig. 1). Here, just thinking about things differently, and more parsimoniously, the naris continues to contact the premaxilla.

According to Wikipedia
MSNM V4047 (in the Museo di Storia Naturale di Milano), described by Dal Sasso and colleagues in 2005, consists of a snout (premaxillae, partial maxillae, and partial nasals) 98.8 centimetres (38.9 in) long from the Kem Kem Beds. Like UCPC-2, it is thought to have come from the early Cenomanian. Arden and colleagues in 2018 tentatively assinged this specimen to Sigilmassasaurus brevicollis given its size. In the absence of associated material, however, it is difficult to be certain which material belongs to which taxon.”


References
dal Sasso C, Maganuco S, Buffetaut E, Mendez MA 2005. New information on the skull of the enigmatic theropod Spinosaurus, with remarks on its sizes and affinities. Journal of Vertebrate Paleontology. 25 (4): 888–896.
Ibrahim N et al. 2014. Semiaquatic adaptations in a giant predatory dinosaur. Science 345 (6204): 1613–1616.
Stromer E 1915. Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wüsten Ägyptens. II. Wirbeltier-Reste der Baharije-Stufe (unterstes Cenoman). 3. Das Original des Theropoden Spinosaurus aegyptiacus nov. gen., nov. spec. Abhandlungen der Königlich Bayerischen Akademie der Wissenschaften, Mathematisch-physikalische Klasse (in German). 28 (3): 1–32.

wiki/Spinosaurus

Hauffiosaurus: convergent with later plesiosaurs

Updated March 28, 2019
with a new old engraving of Anningasaura.

Two misfit plesiosaurs nest together in the LRT
Earlier we looked at Anningsaura (Fig. 6)Vincent and Benson (2012) reported, “In general morphology, NHMUK OR49202 does not resemble any known plesiosaurian taxon.”

Figure 2. The sisters of Anningsaura, Simosaurus and Pistosaurus.

Figure 1. The sisters of Anningsaura, Simosaurus and Pistosaurus. Until today, these provided the only clues as to the post-crania of Anningsaura, of which only the first eight cervicals are known.

Anningasaura 
(originally Plesiosaurus macrocephalus, Lydekker 1889; NHMUK OR49202) represents a completely ‘new’ branch of the plesiosauria in which the orbits virtually cannot be seen in dorsal view and the jugals bend down posteriorly to produce an angled temporal arch (Fig. 1). Moreover the premaxillae were thought to not contact the frontals and the nasals were absent. Benson et al. (2012) created a phylogenetic analysis that nested Anningsasaura at the base of the pliosaur/plesiosaur split with Bobosaurus as the outgroup.

Figure 1. Hauffiosaurus from Vincent 2011 with colors and reconstructions added.

Figure 2. Hauffiosaurus from Vincent 2011 with colors and reconstructions added.

Hauffiosaurus zanoni 
(O’Keefe 2001; Vincent 2011; Early Jurassic; 3.4m long; uncatalogued Hauff museum) is another plesiosaur that, according to Vincent 2011, “does not resemble any known plesiosaurian taxon.” This genus was considered a basal pliosauroid. Here (Fig. 3) the large reptile tree (LRT, 1392 taxa) nests between Anningsaura and Pistosaurus. Benson et al 2012 nested Hauffiosaurus one or two nodes apart from Anningsaura. No taxa in those nodes is currently in the LRT. So the LRT is a close match!

As you might imagine,
the characters in the LRT are not the same as those found in Benson et al. 2012, yet the tree topologies, so much as they can be compared, are nearly identical. This was done without first-hand access to the fossils. So, this methodology works.

Figure 3. Subset of the LRT. Here the clade Eosauropterygia nests Anningsaura with Hauffiosaurus.

Figure 3. Subset of the LRT. Here the clade Eosauropterygia nests Anningsaura with Hauffiosaurus. This nesting demonstrates an early convergence with later pliosaurids.

The skull of Hauffiosaurus is exposed in palatal view
(Fig. 4) and as such gives clear data on the often hidden palatal elements. Overlooked by Vincent 2011, the premaxilla extends to the internal naris, as in other taxa (Fig. 5), like Pliosaurus, also an overlooked connection.

Figure 4. Hauffiosaurus skull in palatal view from Vincent 2011, colors added. Overlooked by Vincent, the premaxilla (yellow) contacts the internal naris

Figure 4. Hauffiosaurus skull in palatal view from Vincent 2011, colors added. Overlooked by Vincent, the premaxilla (yellow) contacts the internal naris

DGS is able to document traits
overlooked by those with first-hand access to the fossils themselves (Figs. 4, 5).

Figure 4. Pliosaurus kevani palate, from Benson et al. 2013, also has an overlooked premaxilla-internal naris contact.

Figure 5. Pliosaurus kevani palate, from Benson et al. 2013, also has an overlooked premaxilla-internal naris contact. Red ellipses encircle the internal nares, probably too small for respiration.

Figure 6. Anningasaura colorized from an old engraving. No other aquatic taxon has such bizarrely curved teeth. This taxon is closely related to Hauffiosaurus.

Figure 6. Anningasaura colorized from an old engraving. No other aquatic taxon has such bizarrely curved teeth. This taxon is closely related to Hauffiosaurus, so it provides insight into the lateral view of Hauffiosaurus.

References
Benson RBJ, Evans M, Druckenmiller PS 2012. Lalueza-Fox, Carles. ed. ”High Diversity, Low Disparity and Small Body Size in Plesiosaurs (Reptilia, Sauropterygia) from the Triassic–Jurassic Boundary”. PLoS ONE 7 (3): e31838. doi:10.1371/journal.pone.0031838
Benson RBJ, et al. (6 co-authors) 2013. A giant pliosaurid skull from the Late Jurassic of England. PLoS ONE 8(5): e65989. doi:10.1371/journal.pone.0065989
Dalla Vecchia FM 2006. A new sauropterygian reptile with plesiosaurian affinity from the Late Triassic of Italy. Rivista Italiana di Paleontologia e Stratigrafia 112 (2): 207–225.
O’Keefe RF 2001. A cladistic analysis and taxonomic revision of the Plesiosauria (Reptilia: Sauropterygia). Acta Zoologica Fennica 213:1–63.
Vincent P 2011. A re-examination of Hauffiosaurus zanoni, a pliosauroid from the Toarcian (Early Jurassic) of Germany. Journal of Vertebrate Paleontology 31(2): 340–351.
Vincent P and Benson RBJ 2012. Anningasaura, a basal plesiosaurian (Reptilia, Plesiosauria) from the Lower Jurassic of Lyme Regis, United Kingdom, Journal of Vertebrate Paleontology, 32:5, 1049-1063.

wiki/Anningasaura
wiki/Hauffiosaurus

 

Sauropod nostrils: Where were they?

Short answer:
For whatever reason, derived sauropods shifted the external naris away from the mouth. It would appear illogical to extend soft nostrils back close to the mouth, as Witmer 2001 proposes, over the exterior of the maxillary basin (Fig. 1), which varies greatly (Fig. 2).

Figure 1. From Witmer 2001 showing brachiosaur sauropod skull, colors added. Witmer suggests the nostril might have been located at point 'B' in the maxillary basin (blue) rather than in the external naris (red).

Figure 1. From Witmer 2001 showing brachiosaur sauropod skull, colors added. Witmer suggests the nostril might have been located at point ‘A’ of ‘B’ in the maxillary basin (blue) rather than in the external naris (red).

Witmer 2001 proposed an anterior nostril position
within the nasal basin anterior to the bony external naris in sauropods (positions A and B in Fig. 1, green dot in Fig. 2) and a similar anterior position in other dinosaurs based on an anterior position in most lepidosaurs, crocs and birds. In every photo example presented by Witmer the nostril forms only a small opening relative to the bony external naris.

Witmer 2001 also provided several exceptions to that pattern:

  1. “Cormorant (Phalacrocorax) simply lacked a ßeshy nostril altogether (a diving adaptation)
  2. The bony nostril of geckos is so small that the fleshy nostril occupied almost its entire extent.
  3. The most significant exception was among monitor lizards (Varanus). Some species (e.g., V. griseus, V. dumerili, V. exanthematicus) have a fleshy nostril located in the middle to caudal half of the much enlarged bony nostril.”
  4. Witmer concludes: “Given the diversity of amniotes, one would expect to find additional exceptions.”

As everyone knows,
all tetrapods are capable of inhaling and exhaling through the mouth, which becomes important in panting for internal cooling and when exercise requires more oxygen. The external naris is principally for olfaction and the anterior position of the nostril within the naris maximizes the amount of soft tissue that can be exposed to incoming odors and pheromones.

Figure 1. Four sauropods with external nares identified in pink, internal nares in blue.

Figure 2. Four sauropods with external nares identified in pink, internal nares in blue, Witmer’s proposed nostril in green. Note the external naris already forms a restriction to the airway. For whatever reasons, more derived sauropods phylogenetically shift the nares away from the mouth. Thus there seems to be little reason to imagine the nostrils maintaining an anterior position, nor any reason to further restrict the dimensions of the nostril. When dipping the head down to drink, the internal naris were able to fill with water that drained into the throat whenever the skull was elevated.

A tracing of the external and internal nares in sauropods
(Fig. 2) and a simplified guess connecting the two in lateral view, shows

  1. the elevation of the external naris (pink) relative to the internal naris (blue)
  2. the spacious airway (blue) in sauropod skulls.
  3. the reduced airway proposed by Witmer (green) if skin extended the external naris to the anterior nasal basin
  4. the easy drainage of rainwater if allowed to directly enter the nostrils (pink) in sauropods (probably unimportant, but thought I’d mention it since most nostrils/nares, except whales and crocs, are anterior to lateral, not dorsal)
  5. When dipping the head down to drink, the internal naris were able to fill with water that drained into the throat whenever the lips were sealed and the skull was elevated. That is marginally different from the ostrich drinking behavior (below).
  6. Based on the ostrich example, the sauropod nostril may have extended from 1/3 to 2/3 the area of the external naris in brachiosaurs, to the entire naris in the relatively small external naris of Diplodocus (Fig. 2).

Witmer 2012 (YouTube video below)
provided an ostrich skull in which tissue labeled ‘airway’ completely filled the external naris.

Unfortunately,
the Witmer video does not show the nostril seen in an ostrich photo (Fig. 3). Confusing. That should have been somehow clarified, because the nostril is present in vivo, not in the µCT scan. Added January 22, 2019: The external naris above is the yellow patch at the far anterior tip of the naris. Thank you JB.

Figure 3. Ostrich skull compared to ostrich head with nostril appearing within the external naris.

Figure 3. Ostrich skull compared to ostrich head with nostril appearing within the external naris. The skull may belong to a younger ostrich with a higher cranium than the adult shown here. Note the nostril is about 1/3 the size of the external naris. This may be instructive considering the small head on the end of a long neck on this ostrich, comparable to the small head and long neck in sauropods.

Added January 22, 2019: The following image of a young ostrich
still does not fit the Witmer 2001 ostrich skull. Even when distorted to fit the skull (Fig. 4) the naris does not match the red patch provided for clarification. Something is wrong here. Who can help?

Figure 4. Baby ostrich naris still does not match patch from Witmer 2012 video.

Figure 4. Baby ostrich naris still does not match patch from Witmer 2012 video.

The small head on the end of a long neck
of an ostrich is analogous to the small head and long neck of sauropods when it comes to breathing and drinking. In the ostrich the nostril is one third the size of the naris and located within the naris, more or less anteriorly. Drinking would have been similarly done, with similar problems to get over, like transferring a throat-full or snout-full of water to the stomach by elevating the head and neck.

In a future post
we’ll look, from a scientist’s perspective, why scientists shy away from attempting to replicate discoveries. On the other hand, I revel in testing published hypotheses because so often they leave their work unfinished or misguided one way or another. All the loose ends need to be tidied up.

References
Witmer LM 2001. Nostril position in dinosaurs and other vertebrates and its significance for nasal function. Science 293, 850-853. PDF

The ichthyosaur(s) with 4 nostrils: Musicasaurus

Maxwell et al. 2015
described a juvenile ophthalmosaur, Muiscasaurus catheti, from the Early Cretaceous of Columbia, and it had a bony process dividing its naris. Online press (BBC.com) described the specimen as having four nostrils (Fig. 1). It does not really have four nostrils, but wait, there’s more…

Figure 1. Muiscasaurus catheti prior to final prep, final prep and diagram. Naris is highlighted.

Figure 1. Muiscasaurus catheti prior to final prep, final prep and diagram. Naris is highlighted.. Compare to Ophthalmosaurus natans in figure 2.

The BBC site reported, 
“The fossil is of an infant only about 3m long. Adults may have reached 5m.” Maybe it is best described as “immature” or a “juvenile” when it is more than half the adult size. It is certainly not an infant.

“I could tell it was a juvenile based on the size of its eyes relative to the rest of the skull,” says author Erin Maxwell of the Natural History Museum in Stuttgart, Germany. “In reptiles, babies have very big eyes and heads compared to their body.”

Of course
adult ichthyosaurs with exceptionally large eyes, like Ophthalmosaurus (Fig. 2) have been known for over a century. Perhaps Dr. Maxwell was misquoted. That happens. Also when we look at Ophthalmosaurus, it has nearly the same naris shape as seen in Muiscasaurus catheter. 

Figure 2. Two variations on Ophthalmosaurus, both with large eyes and one with a peanut-shaped naris, similar to the four-nostril Muiscasaurus.

Figure 2. Two variations on Ophthalmosaurus, both with large eyes and one with a peanut-shaped naris, similar to the four-nostril Muiscasaurus.

Another news source,
the Ulyanovsk Chronicles, recently published a story and image of another “ichthyosaur with four nostrils,” (Fig. 3) from the Aptian (Early Cretaceous, 120 mya) of Sengileevsky paleontological reserve. The site reported [after Google translation], “A preliminary study of a new Museum exhibit conducted by Valentin Fischer (University of Liege, Belgium), [AND] Maxim Arkhangelsky (Saratov state technical University) showed that he loved aikataulu [referred the specimen to?] (Muiscasaurus).” 

Figure 3. A Russian four-nostril ichthyosaur with the pencil resting in the posterior naris.

Figure 3. A Russian four-nostril ichthyosaur with the pencil resting in the posterior naris.

In this new specimen
the anterior and posterior portions of the naris are more completely divided. I wonder if all ichthyosaurs had such a dual naris in soft tissue, but only in these specimens can we find bony support?

References
Maxwell EE, Dick D, Padilla S and Parra ML 2015. A new ophthalmosaurid ichthyosaur from the Early Cretaceous of Columbia. Papers in Palaeontology 2015:1-12.

A tiny naris in Guidraco

Figure 1. Closing in on the naris in Guidraco, an Early Cretaceous ornithocheirid from South America. Colors are naris = pink, maxilla = green, jugal = blue, premaxilla = yellow

Figure 1. Closing in on the naris in Guidraco, an Early Cretaceous ornithocheirid from South America. Colors are naris = pink, maxilla = green, jugal = blue, premaxilla = yellow

Guidraco is related to Ludodactylus, another crested ornithocheirid.

And for those who think the fenestra closer to the antorbital fenestra makes a better naris, I say, “good eye!”

References
Frey E, Martill DM and Buchy M-C 2003. A new crested ornithocheirid from the Lower Cretaceous of northeastern Brazil and the unusual death of an unusual pterosaur: In: Buffetaut, E., and J.-M. Mazin, Eds. Evolution and Palaeobiology of Pterosaurs. – London, Geological Society Special Publication 217: p. 55-63.
Wang X-L, Kellner AWA, Jiang S-X and Cheng X 2012. New toothed flying reptile from Asia: close similarities between early Cretaceous pterosaur faunas from China and Brazil. Naturwissenschaften in press. doi:10.1007/s00114-012-0889-1.

wiki/Ludodactylus

wiki/Guidraco

 

The reduction and duplication of the naris in certain pterosaurs

Most pterosaur paleontologists don’t bother with such details.

The reduction (not assumed confluence) and duplication of the naris in derived pterosaurs (Fig. 1) is not due to neotony (contra Unwin and Lü 2013), but due to phylogeny. Along with phylogenetic size reduction the naris became reduced (Fig. 1) in several pterosaur lineages. Evidently, as in certain birds, like gannets, the naris became less important for certain pterosaur lines.

This is at odds with the origin of pterosaurs when the naris became greatly enlarged compared to outgroups like Cosesaurus. Pterosaurs must have spent more time mouth-breathing, or — in the switch from insect-eating to fish-eating — evolved a way to avoid getting water up the nose.

Figure 1. Click to enlarge. The reduction of the naris (red arrow), the appearance of the secondary naris, and the appearance of the secondary ascending process of the maxilla in a line of scaphognathids, all to the same scale.

Figure 1. Click to enlarge. The reduction of the naris (red arrow), the appearance of the secondary naris, and the appearance of the secondary ascending process of the maxilla in a line of scaphognathids, all to the same scale. N0. 12 is basal to germanodactylids and then beyond to pteranodontids, dsungaripterids and tapejarids, most of which lose the naris. The GMu specimen is basal to ornithocheirids and cycnorhamphids. Scale bar = 1 cm.

And along with the reduction and duplication of the naris, these pterosaurs develop a secondary ascending process in the maxilla (blue arrow), always small. There’s even an ascending process of the jugal (light blue bone) laminated against the ascending process of the maxilla. Yes, the naris does eventually disappear in certain taxa, but the bones around it give away its former position.

 

In all cases but one, the reduction of the naris involved the overall reduction of the pterosaur, regardless of rostrum length. That one case is the lineage of Jianchangnathus,  Pterorhynchus and darwinopterids, which we last discussed here.

 

The secondary naris that frequently develops is nothing more than a tiny hole that did not contribute to respiration. So don’t freak out about the concept.

When you have a good phylogenetic tree, you can see how details like this evolve over time and taxa. Removes the mystery, which some folks still don’t appreciate.

Champsosaurus and its snorkel nose

Choristoderes are a varied clade of mostly aquatic, often croc-like reptiles descending from certain long-snouted younginids, like the BPI-2871 specimen (Fig. 2). Doswellia (Fig. 2) is closely related to choristoderes, splitting off at the base to form its own clade. Diandongosuchus likewise split off early, giving rise to later parasuchids (phytosaurs), proterochampsids and chanaresuchids.

Many from this varied clade of pararchosauriformes had nostrils shifted back from the snout tip, reaching an acme with parasuchians. Champsosaurus (Figs. 1, 2) was different. The naris was located at the very tip, probably to act as a snorkel, in order to breathe without surfacing. Given the unusual morphology of the snout tip, it’s very possible that the reversion to the tip was a secondary adaptation.

Figure 1. Neochoristoderes including Champsosaurus, Simoedosaurus and Ikechosaurus.

Figure 1. Neochoristoderes including Champsosaurus, Simoedosaurus and Ikechosaurus. Premaxilla in yellow. Nasals in pink. Lacrimals in orange. The prefrontals were fused to the nasals. Note: the largest genus here is the most primitive with lateral temporal fenestra oriented laterally and the nares still dorsal on the rostrum.

The identification of the rostral bones in Champsosaurus is controversial. Here we’ll look at some heretical labels for traditional paradigms.

Figure 2. Various choristoderes and their kin with a focus on the bones surrounding the naris and comprising the snout.

Figure 2. Various choristoderes and their kin with a focus on the bones surrounding the naris and comprising the snout. The nostrils migrate posteriorly by convergence in Lazarussuchus and Diandongosuchus.

Traditionally
In Champsosaurus (Fig. 1) the dorsal medial bone is traditionally considered the nasal and the paired bones following it are considered the prefrontals. However if you look at all the closest kin to Champsosaurus it becomes clear that the paired bones remain traditional nasals. The prefrontals are simply missing, likely due to fusion with the nasals. That means the tooth-bearing portions of the premaxilla wrapped completely around the rostrum and nares until they came into contact with the ascending process of the premaxilla, which extends beyond the naris in many related taxa.

Did Champsosaurus once have an antorbital fenestra?
Related taxa, including Diandogosuchus and Doswellia had an antorbital fenestra and there are signs of a nascent or vestigial antorbital fenestra in certain Champsosaurus (Fig. 3). If it’s there, it’s tiny, but worth searching for.

Figure 3. The rostrum of a champsosaur color coded to identify the premaxilla (yellow), nasals (pink), prefrontals (purple) and lacrimals (orange). The vestigial or nascent antorbital fenestrae are in black, along with the snout-tipped nares (at far right).

Figure 3. The rostrum of a champsosaur color coded to identify the premaxilla (yellow), nasals (pink), prefrontals (purple) and lacrimals (orange). The vestigial or nascent antorbital fenestrae are in black, along with the snout-tipped nares (at far right). If anyone has better data, please send it along.

Choristoderes are underrepresented in the fossil record.
So are doswellids and basal parasuchians. What this means, with present data, is basal taxa appear to be large forms, which goes against the grain of evolutionary patterns. These named taxa are all quite derived at their first appearance. I’m guessing we’re likely to find smaller basal and transitional forms, more like the BPI-2781 specimen (Fig. 2) as they become known.

It’s also interesting that the largest choristodere, Simoedosaurus (Fig. 1) has the more primitive skull, with a dorsal set of nares and more laterally-oriented lateral temporal fenestra. The smaller Champsosaurus has the more derived snout tip and more dorsally open lateral temporal fenestrae.

Popping paradigms is what we do here.
If you have data that supports other positions, please send them forward.

Updated were made to today to the post on Varanosaurus and archosauromorph diapsid origins.