New taxa in the lineage of right whales

Tubby right whales
like Eubalaena (Fig. 1) are different from sleek rorquals, like the blue whale (Balaenoptera). Right whales don’t have the huge throat sack that rorquals expand with sea water + krill. Instead longer baleen fringes and huge lower lips filter right whale meals and usually in a horizontal, rather than a vertical, attack formation.

Figure 1. Taxa in the lineage of right whales include Desmostylus, Caperea and Eubalaena. The tiny bit of jugal posterior to the orbit (in cyan) is found in all baleen whales tested so far. The frontals over the eyes are just roofing the eyeballs in Desmostylus, much wider in Caperea and much, much longer in Eubalaena.

Figure 1. Taxa in the lineage of right whales include Desmostylus, Caperea and Eubalaena. The tiny bit of jugal posterior to the orbit (in cyan) is found in all baleen whales tested so far. The frontals over the eyes are just roofing the eyeballs in Desmostylus, much wider in Caperea and much, much longer in Eubalaena.

According to Wikipedia:
“The pygmy right whale (Caperea marginata), a much smaller whale of the Southern Hemisphere, was until recently considered a member of the Family Balaenidae. However, they are not right whales at all, and their taxonomy is presently in doubt. Most recent authors place this species into the monotypic Family Neobalaenidae, but a 2012 study suggests that it is instead the last living member of the Family Cetotheriidae, a family previously considered extinct.”

That 2012 study was by Marx and Fordyce. The large reptile tree (LRT, 1060 taxa) does not support that assignment, perhaps because Marx and Fordyce omitted tenrecs and desmostylians from their whale analysis. At present all cetiotheres in the LRT have straight rostra and mandibles, a far cry from the dipped snout of these taxa. Note the deep baleen in Caperea (Fig. 1). That’s a right whale trait.

Figue 2. Caperea is a transitional taxon between tubby Desmostylus and tubby Eubalaena. Note the tiny manus (flipper). It is neotenous. See text for details. Note the short tail, not much longer than the tail found in Desmostylus.

Figue 2. Caperea is a transitional taxon between tubby Desmostylus and tubby Eubalaena. Note the tiny manus (flipper). It is neotenous. See text for details. Note the short tail, not much longer than the tail found in Desmostylus.

Caperea marginata (The pygmy right whale; Bisconti 2012, Fordyce and Marx 2013) looks like a small blue whale, but has long, inclned ribs, only one lumbar vertbra, and a short tail. The mandible is deep and concave ventrally. Like Eubalaena the lacrimal is deeper than the maxilla. Note the tiny forelimb. The manus has a few extra bones that, when put back together, create a digit 1. Mid-phalanges (3.2, 4.2, 4.3) lost in basal therapsids reappear in this taxon with a netonous tiny manus.

Figure 2. Limusaurus also has four fingers and a scapula with a robust ventral area, like Majungasaurus, but those four fingers are not the same four fingers found in Majungasaurus.

Figure 3. Limusaurus also has an extra digit medial to the other three common to most therapies. We call that digit zero, otherwise found in certain very basal tetrapods only.

We’ve seen this before.
Remember Limusaurus? (If not, check out Fig. 3) That’s the oviraptorid-like theropod with an equally tiny manus provided with an extra medial digit (digit zero). Same thing here provides the reappearance of digit 1, reduced or absent in all ancestors beginning with Mesonyx. And THAT explains the reappearance of manual digit 1 (the thumb) in the right whale, Eubalaena (Fig. 1), the only exception in this clade of thumbless taxa.

Figure x. Desmostylus skull in several views. Note the nasals have a different shape (upper left) than originally traced (lower right). Arrows point to wider mandibles than rostrum.

Figure x. Desmostylus skull in several views. Note the nasals have a different shape (upper left) than originally traced (lower right). Arrows point to wider mandibles than rostrum.

Little things to look for in desmostylians retained by baleen whales

  1. The mandible is wider than the rostrum (Fig. x). That’s where the giant lower lips arise.
  2. A bit of jugal is attached to the front of the squamosal, even when the portion below the orbit is missing.
  3. The reduction of teeth is completed in baleen whales
  4. The ventral portion of the rostrum is visible in lateral view
  5. The anterior tips of the mandibles either have tusks or the alveoli  from which tusks once emerged. Here (Fig. x) the tusks are tiny.
  6. Same with the anterior maxillae, but smaller because those tusks disappear earlier.  Here (Fig. x) the tusks are tiny. Blame it on neotony.
  7. The tail series of Caperea is really quite short (Fig. 2)—and shorter still IF you imagine a former pelvis the size of the one in Desmostylus, now greatly reduced (Fig. 1). And that is a big part of the solution to the lack of a large tail in desmostylians: don’t lengthen the tail…shrink that giant pelvis!!! And blame it on neotony.
Figure 7. Desmostylus jaws with green and blue arrows pointing to buried canine and anterior dentary tusks. Compare to gray whale rostrum in figure 6.

Figure 4. Desmostylus jaws with green and blue arrows pointing to buried canine and anterior dentary tusks. Compare to gray whale rostrum in figure 6.

Figure 8. Gray whale (Eschirctius) anterior rostrum. Green arrow points to the canine alveolus lacking a tooth. Missing mandible teeth would have appeared along anterior rims of the mandibles (blue arrow), as in desmostylians.

Figure 5. Gray whale (Eschirctius) anterior rostrum. Green arrow points to the canine alveolus lacking a tooth. Missing mandible teeth would have appeared along anterior rims of the mandibles (blue arrow), as in desmostylians.

We’ll look at
cetiotheres and rorquals in the next few days.

References
Domning DP, Ray, CE and McKenna, MC 1986. Two new Oligocene desmostylians and a discussion of Tethytherian systematics. Smithsonian Contributions to Paleobiology. 59. pp. 1–56.
Fordyce RE and Marx FG 2013. The pygmy right whale Caperea marginata: the last of the cetotheres. Proceedings of the Royal Society B: Biological Sciences 280(1753):1–6.
Marsh OC 1888. Notice of a new fossil sirenian, from California. American Journal of Science 25(8):94–96.
Reinhart RH 1959. A review of the Sirenia and Desmostylia. University of California Publications in Geological Sciences 36(1):1–146.
Santos G, Parham J and Beatty B 2016. New data on the ontogeny and senescence of Desmostylus (Desmostylia, Mammalia). Journal of Vertebrate Paleontology. doi: 10.1080/02724634.2016.1078344
Tsai C-Hi and Fordyce RE 2015. Ancestor–descendant relationships in evolution: origin of the extant pygmy right whale, Caperea marginata. Biol Lett. 2015 Jan; 11(1): 20140875.

wiki/Caperea
wiki/Desmostylus

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Dingavis: fangs on a basal bird

Here’s an Early Cretaceous bird
at the base of the Odontornithes (toothed neognaths) with premaxillary and anterior dentary teeth developed into fangs, apparently overlooked by the original authors of Dingavis longimaxilla  (IVPP V20284, O’Connor, Wang and Hu 2016). They were more intrigued by the length of the rostrum and did not appear to delve into the details (Figs. 1,2).

Figure 1. Dingavis longimaxilla in situ nests with Hongshanornis at the base of neognath birds.

Figure 1. Dingavis longimaxilla in situ nests with Hongshanornis at the base of neognath birds. This image is about 3/4 full size, so this is a robin-sized bird.

Maybe they rushed through
Attempting a reconstruction helps the mind sort out some of the problems in crushed fossils such as this one. You can try on one idea after another until one seems to fit. 

Figure 2. Dingavis skull. The large anterior teeth were overlooked in the original description. The naris appears to be quite elongate here.

Figure 2. Dingavis skull. The large anterior teeth were overlooked in the original description. The naris appears to be quite elongate here.

It’s worthwhile to compare Dingavis
to its more plesiomorphic sister, Hongshanornis (Fig. 3). Note the four tiny premaxillary teeth and the others lining the jaws.

That beak tip of Dingavis
is similar by analogy to that of the giant petrel, Macronectes. However, the size differences are too great to draw too much of an analogy.

Figure 3. Hongshanornis skull in situ. Note the four tiny premaxillary teeth, two of which enlarge in Dingavis.

Figure 3. Hongshanornis skull in situ. Note the four tiny premaxillary teeth, two of which enlarge in Dingavis.

Wikipedia reports
“Hongshanornis is a member of the group Hongshanornithidae, to which it lent its name. It is closely related to Longicrusavis, which existed alongside Hongshanornis in the Dawangzhangzi ecosystem” In the LRT these taxa are basal to the Late Cretaceous toothed birds, Hesperornis and Ichthyornis. and so appear to be part of the Odontornithes extending to the Early Cretaceous, shortly after the appearance of Archaeopteryx and other Solnhofen birds.

Figure 4. Hongshanornis in situ with drawing from original paper.

Figure 4. Hongshanornis DNHM D2945, in situ with drawing from original paper. Colors added here.

Wikipedia reports
“In 2016, it was suggested that Dingavis might be cogeneric to the closely related genera Changzuiornis and Juehuaornis [Fig. 5] that might have been found in the same formation, in which case Juehuaornis would have priority.”

Figure 5. Juehuaornis does not have premaxillary teeth, so it is not congeneric with Juehuaornis.

Figure 5. Juehuaornis does not have premaxillary teeth, so it is not congeneric with Juehuaornis.

Lacking large anterior fangs,
Juehuanornis (Fig. 5) is not congeneric with Dingavis. 

References
O’Connor JK, Wang M and Hu H 2016.
A new ornithuromorph (Aves) with an elongate rostrum from the Jehol Biota, and the early evolution of rostralization in birds, Journal of Systematic Palaeontology, DOI: 10.1080/14772019.2015.1129518
Zhou Z and Zhang F 2005. Discovery of an ornithurine bird and its implication for Early Cretaceous avian radiation. PNAS 102(52): 18998-19002. doi:10.1073/pnas.0507106102

wiki/Hongshanornis
wiki/Dingavis

 

Eogranivora has chicken feet and 6 fingers

Higher resolution data
and DGS color overlays reveal that the Early Cretaceous chicken, Eogranivora, has overlooked manual and pedal digits (Fig. 1). Digit zero makes an appearance here. Fusion was much less apparent than traced. Pedal digit 1 was overlooked, despite the tracing of pedal 1.1.

Figure 1. The manus and pes of the Early Cretaceous chicken, Eogranivora. Here digit 0 makes an appearance on the manus along with vestigial digits 4 and 5. On the pes pedal digits 1 (cyan) and 5 (purple) were overlooked. Here DGS reveals them. Overlay changes ever 5 seconds. The process of fusion implied by the drawings is not yet complete under DGS.

Figure 1. The manus and pes of the Early Cretaceous chicken, Eogranivora. Here digit 0 makes an appearance on the manus along with vestigial digits 4 and 5. On the pes pedal digits 1 (cyan) and 5 (purple) were overlooked. Here DGS reveals them. Overlay changes ever 5 seconds. The process of fusion implied by the drawings is not yet complete under DGS.

Earlier we looked at Eogranivora and nested it with Gallus the extant chicken using low-rez data. Here even the skull is updated with plate and counter plate revealing data overlooked by original authors (Figs. 2,3 for those who don’t review updated blog posts).

Figure 1b. Eogranivora skull in situ (plate and counterplate) in higher resolution.

Figure 2. Eogranivora skull in situ (plate and counterplate) in higher resolution.

Figure 1c. Skull of Eogranivora in situ and reconstructed using DGS, replacing a lower resolution attempt. Some details added for the palate here.

Figure 3. Skull of Eogranivora in situ and reconstructed using DGS, replacing a lower resolution attempt. Some details added for the palate here.

Eogranivora edentulata (Zheng et al. 2018; Early Cretaceous, Yixian Fm. Aptian, 125 mya; STM35-3) was earlier referred to Hongshanornis by (Zheng et al. 2011) who found evidence for an avian crop, along with feathers, gastroliths and seeds in the present specimen. Distinct from the holotype of HongshanornisEogranivora is toothless. This specimen is a direct link from the Early Cretaceous to the present day. With larger wings and a smaller body Eogranivora would have been a better flyer than extant chickens.

Figure 2. Gallus, the chicken, nests as a sister to the Early Cretaceous, Eogranivora, also a seed-eater.

Figure 4.. Gallus, the chicken, nests as a sister to the Early Cretaceous, Eogranivora, also a seed-eater. Note the length of the robust scapula.

With robust ribs
and a scapula extending back to the pelvis, Gallus, the chicken stands out from most birds. Eogranivora, if I have this right, also has robust ribs and an extended scapula (Fig. 5). Preservation is a funny thing when plates are split from counter plates. Sometimes we see the bone. Sometimes we see an impression of bone. Sometimes the bone splits down the middle and we see the inside of the bone. Here the parts of the scapula appear to be below and above the ribs, hence, my trepidation.

Figure 5. The crop, gizzard, sternum and scapulae of Eogranivora with DGS color overlays. Some guesswork here.

Figure 5. The crop, gizzard, sternum and scapulae? of Eogranivora with DGS color overlays. Some guesswork here. Some vertical bones apparently cross over and under the horizontal ribs. 

References
Zheng X, O’Connor JK, Wang X, Wang Y and Zhou Z 2018. Reinterpretation of a previously described Jehol bird clarifies early trophic evolution in the Ornithuromorpha. Proceedings of the Royal Society B 285: 20172494
Zheng X-T, Martin LD, Zhou Z-H, Burnham DA, Zhang F-C and Miao D 2011. Fossil evidence of avian crops from the Early Cretaceous of China. Proceedings of the National Academy of Sciences. USA 108: 15 904–907

wiki/Eogranivora
wiki/Gallus

Eogranivora: an Early Cretaceous chicken!

Updated February 5, 2018 with higher resolution data of the skull. Not much changed. Eogranivora is still a chicken sister. 

This was predicted
by the large reptile tree (LRT, 1054 taxa, subset Fig. 3) and overlooked by the original authors due to a lack of an accurate tracing of the skull. Extant birds had their origin in the Early Cretaceous… they just have not been discovered there, until now.

Figure 1. Eogranivora from Zheng et al. 2018 with DGS colors added and reconstructed. Except for the longer wings and straight rostrum, most traits found here are also found in Gallus the chicken (figure 2).

Figure 1. Eogranivora from Zheng et al. 2018 with DGS colors added and reconstructed. Except for the longer wings and straight rostrum, most traits found here are also found in Gallus the chicken (figure 2).

Figure 1b. Eogranivora skull in situ (plate and counterplate) in higher resolution.

Figure 1b. Eogranivora skull in situ (plate and counterplate) in higher resolution. Colors correspond to reconstructed skull in figure 1c. Colors sure do clarify skulls like this one.

Figure 1c. Skull of Eogranivora in situ and reconstructed using DGS, replacing a lower resolution attempt. Some details added for the palate here.

Figure 1c. Skull of Eogranivora in situ and reconstructed using DGS, replacing a lower resolution attempt. Some details added for the palate here. It’s still a chicken sister.

Eogranivora edentulata (Zheng et al. 2018; Early Cretaceous, Yixian Fm. Aptian, 125 mya; STM35-3) was earlier referred to Hongshanornis by (Zheng et al. 2011) who found evidence for an avian crop, along with feathers, gastroliths and seeds in the present specimen. Distinct from the holotype of Hongshanornis, Eogranivora is toothless.

Figure 2. Gallus, the chicken, nests as a sister to the Early Cretaceous, Eogranivora, also a seed-eater.

Figure 2. Gallus, the chicken, nests as a sister to the Early Cretaceous, Eogranivora, also a seed-eater.

The authors
included Gallus the chicken (Fig. 2) in their taxon list, but failed to nest the two taxa together… even after noting that Eogranivora was a seed eater. So, this one cannot be attributed to taxon exclusion, but taking a look at their tracing of the specimen (Fig. 1) indicates they put little to no effort into deciphering the crushed bones of this complete and articulated specimen. They could have used a little DGS, which always comes with a reconstruction (Fig. 1 skull, pes).

With larger wings and a smaller body
Eogranivora would have been a better flyer than extant chickens. And that’s to be expected.

Figure 3. Eogranivora nests with Gallus the chicken in the LRT, confirming the origin of Ornithuromorpha back to the Early Cretaceous.

Figure 3. Eogranivora nests with Gallus the chicken in the LRT, confirming the origin of Ornithuromorpha in the Early Cretaceous, which makes it that much easier to have highly derived penguins appear in the Paleocene.

You may remember
the highly derived penguins first appear in the Paleocene. The appearance of volant chickens in the Early Cretaceous makes this easier (more gradual), and falsifies the earlier widely-held hypothesis of a fast radiation of extant birds shortly after the K-T extinction event.

This could have been a big news event.
Unfortunately, it falls to bloggers to make the importance of this fossil widely known.

References
Zheng X, O’Connor JK, Wang X, Wang Y and Zhou Z 2018. Reinterpretation of a previously described Jehol bird clarifies early trophic evolution in the Ornithuromorpha. Proceedings of the Royal Society B 285: 20172494
Zheng X-T, Martin LD, Zhou Z-H, Burnham DA, Zhang F-C and Miao D 2011. Fossil evidence of avian crops from the Early Cretaceous of China. Proceedings of the National Academy of Sciences. USA 108: 15 904–907

wiki/Eogranivora

The hands of Juravenator

There’s a tiny disarticulated fourth finger hidden in there…
that was originally overlooked (Fig. 1, in pink).

Figure 1. The hands of Juravenator in situ and reconstructed. Note on the left hand, digit 2 is lateral. Somehow digit 3 has moved below it.

Figure 1. The hands of Juravenator in situ and reconstructed. Note on the left hand, digit 2 is lateral. Somehow digit 3 has moved below it. The grayscale drawing is from the original paper.

Oddly, in the left hand
(Fig. 1) digit 3 ended up between digits 1 and 2.

See how DGS (digital graphic segregation) can be helpful?
Try it yourself. It just clarifies things and make reconstructions easy without changing the traced data, even by one pixel.

Careful readers will note
that few PILs (parallel interphalangeal lines) can be drawn through the joints here. Probably they come into alignment only when the fingers are curled (flexed) as in the human hand (try it yourself!). I say ‘probably’ because these need to be 3D modeled to test the possibility. Metacarpals do align. So do m1.2, m2.2 and m3.3.

Figure 4. Juravenator reconstructed. Note the many similarities with Compsognathus (Fig. 3).

Figure 2. Juravenator reconstructed. Note the many similarities with Compsognathus (Fig. 3).

References
Chiappe LM and Göhlich UB 2010. Anatomy of Juravenator starki (Theropoda: Coelurosauria) from the Late Jurassic of Germany.Neues Jahrbuch für Geologie und Paläontologie – Abhandlungen, 258(3): 257-296. doi:10.1127/0077-7749/2010/0125
Göhlich UB and Chiappe LM 2006. A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago. Nature 440: 329-332.
Göhlich UB, Tischlinger H and Chiappe LM 2006. Juravenator starki (Reptilia, Theropoda) ein nuer Raubdinosaurier aus dem Oberjura der Suedlichen Frankenalb (Sueddeutschland): Skelettanatomie und Wiechteilbefunde. Archaeopteryx, 24: 1-26.

wiki/Compsognathus
wiki/Juravenator

 

Another furcula in a bigger Compsognathus

Yesterday we looked at overlooked bits and pieces in the holotype Compsognathus. Today, pretty much the same with the newer larger specimen.

Figure 1. Forelimb of the large Compsognathus CM79. Here DGS recovered a digit 4, feather impressions, a furcula and sternum overlooked originally.

Figure 1. Forelimb of the large Compsognathus CNJ79. Here DGS recovered a digit 4, feather impressions, a dorsal scapula tip, a furcula and sternum overlooked originally.

The much larger and probably not congeneric
CNJ79 specimen of Compsognathus ((Bidar et al. 1972b; Peyer 2006; CNJ79; Late Jurassic) also has a few overlooked bits and pieces. 

Figure 1. The large (from Peyer 2006) and small Compsognathus specimens to scale. Several different traits nest these next to one another, but at the bases of two sister clades. Note the differences in the forelimb and skull reconstructions here. There may be an external mandibular fenestra. Hard to tell with the medial view and shifting bones.

Figure 2. The large (from Peyer 2006) and small Compsognathus specimens to scale. Several different traits nest these next to one another, but at the bases of two sister clades. Note the differences in the forelimb and skull reconstructions here.

Another tiny furcula
was identified by the authors in Juravenator (Fig. 3), a close relative of the two Compsognathus taxa.

Figure 3. Juravenator clavicles/furcula identified by Göhlich et al. 2006.

Figure 3. Juravenator clavicles/furcula identified by Göhlich et al. 2006, similar to those found in Compsognathus.

Whereas
the little holotype Compsognathus gave rise to ornithomimosaurs and tyrannosaurs, the large Compsognathus gave rise to Juravenator, Sinosauropteryx, therizinosaurs and oviraptorids.

Figure 4. Juravenator reconstructed. Note the many similarities with Compsognathus (Fig. 3).

Figure 4. Juravenator reconstructed. Note the many similarities with Compsognathus (Fig. 3).

References
Bidar AL, Demay L and Thomel G 1972b. Compsognathus corallestris,
une nouvelle espèce de dinosaurien théropode du Portlandien de Canjuers (Sud-Est de la France). Annales du Muséum d’Histoire Naturelle de Nice 1:9-40.
Chiappe LM and Göhlich UB 2010. Anatomy of Juravenator starki (Theropoda: Coelurosauria) from the Late Jurassic of Germany.Neues Jahrbuch für Geologie und Paläontologie – Abhandlungen, 258(3): 257-296. doi:10.1127/0077-7749/2010/0125
Göhlich UB and Chiappe LM 2006. A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago. Nature 440: 329-332.
Göhlich UB, Tischlinger H and Chiappe LM 2006. Juravenator starki (Reptilia, Theropoda) ein nuer Raubdinosaurier aus dem Oberjura der Suedlichen Frankenalb (Sueddeutschland): Skelettanatomie und Wiechteilbefunde. Archaeopteryx, 24: 1-26.
Peyer K 2006. A reconsideration of Compsognathus from the upper Tithonian of Canjuers, southeastern France, Journal of Vertebrate Paleontology, 26:4, 879-896,

wiki/Compsognathus
wiki/Juravenator

The premaxilla of Halszkaraptor: shorter than they thought.

Figure 1. Halszkaraptor images from Cau et al. Note the reconstruction with a too long premaxilla (red circle).

Figure 1. Halszkaraptor images from Cau et al. Note the reconstruction with a too long premaxilla (red circle). Short nore: the gastralia shown here evidently were not present in the fossil, but were imagined into place. Halszkaraptor nests with Shuvuuia, which also lacks gastralia. Let me know if either is incorrect. 

Originally described
by Cau et al. 2018 with 11 (x2) premaxillary teeth, Halszkaraptor stands out for having seven too many teeth in the premaxilla compared to all sister candidates. A closer look at the premaxilla reveals a mouth full of teeth, but the premaxilla has only four (x2) teeth. Cau et al. were kind enough to publish several views of the rostrum (Fig. 2).

Figure 1. The premaxilla and maxilla of the troodontid dinosaur Halszkaraptor shows the premaxilla is shorter with fewer teeth than originally described.

Figure 2. The premaxilla and maxilla of the troodontid dinosaur Halszkaraptor shows the premaxilla is shorter with fewer teeth than originally described.

Not alone on the cladogram.
Halszkaraptor is joined by Haplocheirus, which also has a similar short premaxilla (Fig. 3).

Figure 3. Haplocheirus nests close to Halszkaraptor in the LRT and has a similar short premaxilla.

Figure 3. Haplocheirus nests close to Halszkaraptor in the LRT and has a similar short premaxilla.

References
Cau A, et al. 2017. Synchrotron scanning reveals amphibious ecomorphology in a new clade of bird-like dinosaurs. Nature. doi:10.1038/nature24679

wiki/Halszkaraptor
wiki/Shuvuuia
wikiHaplocheirus