Cornwallius: not a desmostylian, an ancestor to desmostylians

These taxa
are part of the a recent review of mysticete (baleen whale) ancestors you can read about here, here and here.

Cornwallius sookensis (originally Desmostylus sookensis, Hay 1923, Cornwall 1922; Beatty 2006a, b; Early Oligocene, 25 mya; Fig. 1) was originally and traditionally considered a desmostylian (Fig. 3). Here it nests with Cambaytherium (Fig. 2), both basal to anthracobunids like Janjucetus. These taxa have a narrow skull and a deep jugal beneath the squamosal. The nares are anterior, rather than dorsal in location.

Figure 1. Adult Cornwallius look more like desmostylians. Juveniles look more like anthracobunids. Both are descendant taxa.

Figure 1. Adult Cornwallius look more like desmostylians. Juveniles look more like anthracobunids. Both are descendant taxa.

Note the resemblance
(lack of a downturned snout) on the juvenile to Cambaytherium (above). Apparently, neotony produces a straights-snout anthracobunid. Otherwise it evolves to the tusky, droop-snout, desmostylian grade.

Figure 2. Cambaytherium with a an alternate rostrum reversing taphonomic shifts.

Figure 2. Cambaytherium with a an alternate rostrum reversing apparent taphonomic shifts.

Beatty 2006
produced the following cladogram (Fig. 3) in which desmostylians are derived from the Moeritherium/Elephas clade. In the large reptile tree (LRT, 1163 taxa) cambaytheres and desmostylians arise from mesonychids and hippos.

Figure 2. From Beatty 2006b, a phylogeny of desmostylians derived from moeritherium, an aquatic relative of elephants and sirenians (manatees). Actually desmostylians arise from cambaytheres and anthracobunids, arising from hippos and mesonychids. 

Figure 3. From Beatty 2006b, a phylogeny of desmostylians derived from moeritherium, an aquatic relative of elephants and sirenians (manatees). Actually desmostylians arise from cambaytheres and anthracobunids, arising from hippos and mesonychids.

References
Beatty, BL 2006a. Rediscovered specimens of Cornwallius (Mammalia, Desmostylia) from Vancouver Island, British Columbia, Canada. Vertebrate Palaeontology. 1(1):1–6.
Beatty, BL 2006b. Specimens of Cornwallius sookensis (Desmostylia, Mammalia) from Unalaska Island, Alaska. Journal of Vertebrate Paleontology. 26(3):785–87.
Cooper LN, Seiffert ER, Clementz M, Madar SI, Bajpai S, Hussain ST, Thewissen JGM 2014. Anthracobunids from the Middle Eocene of India and Pakistan Are Stem Perissodactyls. PLoS ONE. 9 (10): e109232. doi:10.1371/journal.pone.0109232. PMID 25295875.
Cornwall IE 1922. Notes on the Sooke Formation, Vancouver Island, B.C. Canadian Field Naturalist. 36:121–23.
Hay OP 1923. Characteristics of sundry fossil vertebrates. Pan-American Geologist. 39:101–120.
Kumar K 1991. Anthracobune aijiensis nov. sp. (Mammalia: Proboscidea) from the Subathu Formation, Eocene from NW Himalaya, India”. Geobios. 24 (2): 221–39. doi:10.1016/s0016-6995(91)80010-w. OCLC 4656806310.
Rose, KD et al. (8 other authors) 2014. Early Eocene fossils suggest that the mammalian order Perissodactyla originated in India. Nature Communications. 5 (5570). doi:10.1038/ncomms6570.

wiki/Cambaytherium
wiki/Cornwallius

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Aetiocetus: it’s supposed to be a baleen whale ancestor

This is going to be another paleo story about taxon exclusion.
Earlier we looked at paleoworkers trying to nest turtles among diapsids and pterosaurs among archosaurs… but this only happens when more closely related taxa are overlooked or omitted. In the case of the toothed archaic whale, Aetiocetus (Fig. 1), it sure looks like a good candidate for baleen ancestry. The palate was wide, triangular and flat. Unfortunately there are better candidates that were overlooked. Details below.

Figure 1. Three species attributed to Aetiocetus. Other workers considere these basal to baleen whales, but they don't include tenrecs and desmostylians in their analyses.

Figure 1. Three species attributed to Aetiocetus. Other workers considere these basal to baleen whales, but they don’t include tenrecs and desmostylians in their analyses. The teeth of A. polydentatus are simple cones, as in modern toothed whales.

Wikipedia reports:
Aetiocetus is a genus of extinct basal mysticete (baleen whale (late Oligocene, 30 mya). The large reptile tree (LRT, 1161 taxa) nests it with other toothed whales, far from mysticetes. Some traits that distinguish Aetiocetus from other toothed whales include:

  1. the nostrils of the whale had migrated further back on the skull than seen in archaeocetes, but not so far as in modern whales.
  2. no more than three small denticles on the anterior and posterior margins of the posterior upper teeth.
  3. postcanine teeth heterodont.
  4. The base of the rostrum, or snout, of the whale, is greater than 170% of the width of the occipital condyles where the skull meets the neck.
  5. notch by the internal nostrils formed of the palatine, pterygoid, and vomer bones
  6. coronoid process of the dentary well developed
  7. zygomatic arch is expanded anteriorly and posteriorly but is narrow at the middle.
  8. mandibular symphysis not fused.
  9. descending process of the maxilla becomes a toothless plate below the orbit.
  10. wide rostrum

According to Wikipedia,
all these features are functionally related to filter-feeding with baleen and are hallmarks of the Mysticeti. The presence of teeth seems ‘paradoxical’ to these workers. Unfortunately, this hypothetical relationship is recovered only in the absence of desmostylians. 

According to the National Library of Medicine
“All bones possess larger or smaller foramina (openings) for the entrance of the nourishing blood-vessels.”

According to Marx et al. 2016:
“Aetiocetids have previously been proposed as the most basal mysticetes to possess baleen, the key adaptation of modern whales. More specifically, the widespread occurrence of palatal nutrient foramina (in Aetiocetus, Fucaia and Morawanocetus), which in extant mysticetes supply the baleen rack, has been used to infer the existence of an incipient baleen structure between or just lingual to the teeth (Deméré and Berta, 2008; Deméré et al., 2008). While such an interpretation is possible, it also remains untested: just as the origin of feathers in non-avian dinosaurs does not mark the beginnings of flight, so the appearance of palatal foramina in mysticetes need not indicate the presence of baleen. Instead, the foramina of aetiocetids could, for example, have supplied its immediate predecessor – namely, well-developed gums, the presence of which is indicated both by the strongly emergent teeth of early mysticetes (Deméré and Berta, 2008; Fitzgerald, 2010) and, possibly, the largely unworn incisor of NMV P252567.”

Baleen was not found in any specimen of Aetiocetus. 
The presence of baleen is inferred from the presence of nutrient foramina. If so, then baleen had two convergent origins and Aetiocetus represents a dead end, leaving no modern descendants. If nutrient foramina only fed the skin and other tissues that lined the jaws, then no baleen was present.

Baleen WAS found
in the basal mysticete, Miocaperea (Bisconti 2012, skull 1 meter long; Miocene). Traditionally whale workers consider taxa like Caperea and Miocaperea highly derived because desmostylians are not included in their analyses. By contrast, the LRT finds these to be basal mysticetes, Caperea for right whales and Miocaperea for all other mysticetes. Most studies nest Caperea with right whales (clade: Balaenoidea; Demere et al. 2005, Churchill et al. 2012, Ekdale et al. 2011. Marx 2010, did not. All wrongly assume Odontoceti as the outgroup.

Figure 4. The caption for this photo is: "Brian Beatty measuring the jaws of one of our toothed mysticetes. Photo by R. Boessenecker."

Figure 2. The caption for this photo is: “Brian Beatty measuring the jaws of one of our toothed mysticetes. Photo by R. Boessenecker.” This was the traditional view of mysticete origins prior to the addition of desmostylians to the LRT.

The image above
is from  the CCNHM blogsite and the caption for the photo is: “Brian Beatty measuring the jaws of one of our toothed mysticetes. Photo by R. Boessenecker.” Perhaps unknown to Professor Beatty, this is true only in the absence of desmostylians from phylogenetic analysis, an easy mistake to make prior to the entry of desmostylians to the LRT. Various authors have been bending over backwards trying to discover the origin of mysticetes among toothed whales. But they cannot be discovered there. Mysticetes arise from desmostylians, taxa studied by Professor Beatty, but the mysticete connection was not realized.

And that, again demonstrates the value of the LRT,
which permits taxa that have never been tested together to nest together. Taxon inclusion solves every problem in paleontology.

Chronology
This is always a problem due to the rarity of fossils, typically (but not always) recovered as late survivors long after initial radiations. These are taxa recovered by the LRT in the lineage of mysticetes.

  1. Mesonyx: Paleocene or earlier
  2. Ocepeia: Paleocene
  3. Cambaytherium: Eocene
  4. Anthracobune: Eocene
  5. Desmostylus: Oligocene
  6. Cetotherium: Oligocene
  7. Miocaperea: Late Miocene
  8. Caperea and others: Recent

Characters that separate aetiocetids from cetotheres:

  1. Skull shorter than half the presacral length
  2. Snout not constricted
  3. Premaxilla/maxilla notch less than 25º
  4. Naris angle 30-90º but dorsal
  5. Nasals subequal to frontals
  6. Orbit shape in lateral view at least half longer than tall
  7. Frontals without posterior processes
  8. Postparietals angled from the dorsal plane
  9. Tabulars absent
  10. Squamosal descending process at right angle
  11. Frontals and parietals both fused
  12. Occiput far posterior to quadrate articulation
  13. Opisthotics descend
  14. Vomernasal (or other anterior palatal opening) separate from choanae (internal narial opening) by maxilla
  15. Premaxilla teeth present and robust
  16. Last maxillary tooth present and anterior to orbit
  17. Some cervical neural spines taller than centra
  18. 10th caudal length not > chevron depth
  19. Interclavicle/sternal elements present
  20. Scapula not robust
  21. Manual digit 1 present

Interesting tidbits
The coronoid process becomes larger in two tested cetotheres, but not the basal Cetotherium. You wouldn’t think baleen whales would need a tall coronoid process (used for biting), and most don’t have one, but Tokharia and Yamatocetus do.

It only takes the deletion of a few desmostylians to nest baleen whales with toothed whales, due to the large number of similar traits (which is why we call them all ‘whales’. Conversely it only takes the deletion of a few archaic whales to nest odontocetes with baleen whales, as I discovered through testing these options.

For more heretical desmostylian information,
click here.

References
Bisconti M 2012. Comparative osteology and phylogenetic relationships of Miocaperea pulchra, the first fossil pygmy right whale genus and species (Cetacea, Mysticeti, Neobalaenidae). Zoological Journal of the Linnean Society 166: 876-911.
Buchholtz E 2010. Vertebral and rib anatomy in Caperea marginata: Implications for evolutionary patterning of the mammalian vertebral column. Marine Mammal Science 27: 382-397.
Churchill M, Berta A, Deméré TA 2012. The systematics of right whales (Mysticeti: Balaenidae). Marine Mammal Science 28: 497-521.
Deméré TA, Berta A and McGowen MR 2005. The taxonomic and evolutionary history of modern balaenopteroid mysticetes. Journal of Mammalian Evolution 12: 99-143.
Ekdale E G, Berta A and Deméré TA 2011. The comparative osteology of the petrotympanic complex (ear region) of extant baleen whales (Cetacea: Mysticeti). PLoS ONE 6:1-42.
Emlong D 1966. A new archaic cetacean from the Oligocene of Northwest Oregon. Bulletin of the Museum of Natural History, University of Oregon. 3: 1–51.
Fitzgerald EMG 2012. Possible neobalaenid from the Miocene of Australia implies a long evolutionary history for the pygmy right whale Caperea marginata (Cetacea, Mysticeti). Journal of Vertebrate Paleontology 32:976-980.
Marx FG 2011. The more the merrier? A large cladistic analysis of mysticetes, and comments on the transition from teeth to baleen. Journal of Mammalian Evolution 18:77-100.
Marx et al. 2016. Suction feeding preceded filtering in baleen whale evolution. Memoirs of Museum Victoria 75: 71–82.
Van Valen L 1968. Monophyly or diphyly in the origin of whales. Evolution. 22 (1):37–41.

wiki/Aetiocetus

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

 

Duck Origins

Figure 1. Click to enlarge. Duck origins recovered by the LRT. Duck descendants were long-legged walkers and later waders.

Figure 1. Click to enlarge. Duck origins recovered by the LRT. Duck descendants were long-legged walkers and later waders.

Traditional bird phylogenies
nest ducks (genus: Anas) with chickens (genus: Gallus) and screamers (genus: Anhima) close to the base of all neognath birds. 

In the large reptile tree (LRT, 1158 taxa) ducks are not primitive, but arise from a long series of long-legged, increasingly duck-like ancestors including the widely acknowledged proximal ancestor Presbyornis. Hopefully the illustration above (click to enlarge) will clarify the issue in a simple, graphic fashion, as recovered by the LRT.

This is where morphology provides
a readily visible gradual accumulation of traits in derived taxa that is often missing from DNA studies. And yes, it should be this easy.

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

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

Basal mammals: Guess what they evolved to become.

Can you guess
(or do you know) which of these taxa evolved to become a human? a killer whale? a rabbit? a giraffe? a bat? a pangolin?

Figure 1. Can you guess which of these taxa evolved to become a human? a killer whale? a rabbit? a giraffe?

Figure 1. Can you guess which of these taxa evolved to become a human? a killer whale? a rabbit? a giraffe?

H. Onychodectes – basal to all large herbivorous mammals, including giraffes.

G. Maelestes – basal to tenrecs and toothed whales.

F. Tupaia – basal to the gnawing clade including rodents and rabbits.

E. Ptilocercus – basal to Primates, including humans (but note the loss of all premaxillary teeth in this extant taxon).

D. Palaechthon – basal to flying lemurs, bats and pangolins.

C. Monodelphis – basal to all placental mammals.

B. Asioryctes – basal to Monodelphis and all placental mammals.

A. Eomaia – basal to all therian mammals (placentals + marsupials).

These are the basalmost taxa
in various clades of Eutherian (placental) mammals. Not a lot of difference to start (which makes scoring difficult). So much potential at the end. Eomaia goes back to the Early Cretaceous, so it’s not difficult to imagine the radiation of these taxa throughout the Cretaceous.

This falls in line with
the splitting of the African golden mole (Chrysochloris) from its South American sister, Necrolestes, a diversification, migration and split that had to happen before Africa split from South American in the Early Cretaceous.

Sharp-eyed readers
will note the re-identification of bones and teeth in Palaechthon, Ptilocercus and Tupaia. It’s been a long weekend trying to figure out long-standing problems in this portion of the LRT. Some of these taxa were some of the first studied and my naiveté was the source of the earlier disinformation, now corrected. If you see any errors here, please advise and, if valid, repairs will be made.