Ammonites mayorianus was taken by Bayle as the genotype of this genus. Of it de Grossouvre (19, p. 171) says, “I keep the name Puzosia for the forms of a group of ammonites (subplanulata) which have a moderate umbilicus the whorls of which present transverse furrows and sickle-shaped ribs, which, however, are absent near the umbilicus and are marked only on the external region of the flanks. The suture-line offers a complete similarity to that of Desmoceras but is more reduced, and the first lateral lobe is longer than the ventral lobe. The lobes are trifid, and are somewhat more upright than in Desmoceras. The saddles, which are almost all similar, are divided into two parts by a deep lobule.” He takes the suture-line of D. subplanulatum as typical. Sarasin (29A, p. 793) says that, as the genus had not been clearly defined, it had been little adopted by palaeontologists. He characterizes it as follows: “La coquille est
moyemment involutée avec les tours arrondis ou légèrement aplatés sur les côtés, toujours arrondis sur le pourtour externe, le pourtour de l'ombilic n'est jamais caréné et generalment arrondi, les tours sont marqués de nombre variable des constrictions droits ou flexueuses et regulièrement espacées entre les sillons. La coquille est tantôt Iissée tantôt ornée de fines côtes, attenuée sur la partie interne des tours. Les cloisons sont toujours très découpées, le lobe ventral est le même longueur ou un peu plus court que le premier latéral; la selle ventral trés reserrée à sa base s'élargit à la partie supérieure qui est profondement divisée par un lobe accessoire. Le premier lobe latéral est symétrique ou subsymétrique; la première selle latérale est généralment un peu plus elevée que la selle ventrale; sa partie interne est presque constamment plus haute que sa partie externe; le second lobe latéral, moins long et large que le premier, est toujours très disymmétrique; la deuxième selle latérale est moins haute que la précédente, elle est encore trés découpée. Ensuite viennent trois à cinq lobes auxiliaires qui sont tantôt droits ou tantôt au contraire très obliques.”
He classifies Desmoceras in four groups—(1) D. difficile, (2) D. beudanti, (3) D. emmerici, (4) D. mayorianum d'Orb. = Amm. planulatus Sow. The last two of these divisions are considered by him to constitute the subgenus Puzosia.
Zittel (11A, p. 465) divided the genus Desmoceras into five groups—(1) D. beudanti, (2) D. difficile, (3) D. emmerici, (4) D. planulatum, (5) D. gardeni. Kilian and Reboul refer the beudanti and difficile groups to the family of Hoplitidae, the mayoriana and angladei groups to the Phylloceratidae.
Kossmat in 1897 (28, p. 106) distinguishes between three groups of Desmoceratids: (1) Desmoceras emmerici Rasp. with a very regular suture-line. The separate lobes and saddles decrease little by little and extend to the umbilicus. (2) D. planulatum Sowerby (Puzosia Bayle). A distinctly-developed depressed umbilical lobe. The external lobe is almost always a good deal shorter than the first lateral lobe, and this makes it appear as though the external saddle were inclined outwards. The various lobe elements are not arranged with any regularity. He states that this group is closely related to Ammonites beudanti d'Orb. on the one hand, and with Holcodiscus through H. pondicherryianus on the other, as well as with Pachydiscus. (3) D. gardeni (Hauericeras de Grossouvre) includes keeled forms from the Upper Chalk, which in their other characters come very close to the group Ammonites planulatus.
Kihan and Reboul make the following comment (46, p. 17): “On réunit souvent á tort nous semble-t-il, en une même groupe, les Desmoceras s. str. (groupe beudanti-difficile) et les Puzosia (P. angladei, P. mayoriana, etc.) ces deux rameaux ne semblent cependant avoir entre eux aucun rapport genetique; le premier dérive sans doute des Holplitides (sensu lato) specialement de Leopoldia, et le second peutêtre des Phylloceratides par l'intermediare de Sowerbyceras (Tortisulcati) et de Silesites?”
Zittel in 1895 and Hyatt in 1913 included Puzosia and Hauericeras in the Desmoceratidae. This relationship was the one adopted also by Yabe in 1903 (37, p. 30).
Pervinquière (“Sur quelques Ammonites du Crétacé Algerien,” Mem. Soc. Geol. Fr., vol. 17, 1910, p. 31) appears to use Puzosia in the sense defined by Sarasin.
Jacob (44, p. 26) divides Desmoceras into four groups, the last of which is Puzosia, with the genotype P. mayoriana, which has a symmetrical lobe. This author (p. 55) places several of Sarasin's second group of Desmoceras in Sonneratia, which is referred to the Hoplitidae.
Spath in 1922 makes the following remark (54, p. 120): “The genera Pachydiscus, Parapachydiscus, Parapuzosia, Kossmaticeras, and the many allied developments can all be derived from Desmoceratid stocks which persisted during the Upper Cretaceous.”
In spite of the weight of these authoritative opinions, and with comparatively a small amount of material to study, the author, relying on the character of the suture-line (both external and internal), as well as on the form of the shell, is inclined to regard Puzosia, Hauericeras, and Maorites n. gen. as derived from the Hoplitidae sensu lato.
Ammonites durga Forbes, in Stol. (11, p. 143, pl. 71, figs. 6, 7).
Puzosia compressa Koss. (28, p. 119, Taf. 18, fig. 4 = Ammonites durga Forbes, in Stol.).
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|Height of last whorl||52||36||64||34|
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A, Puzosia angusta n. sp., Bull's Pomt, Kaipara Harbour, N.Z.; B, Puzosia compiessa Koss. (28, p. 119).
The dimensions given above emphasize the feature of the high and narrow whorl, which seems to be more extreme than in any other species of this genus of which descriptions are available. Involution nearly one-half, and whorls rapidly increasing in height. Flanks nearly flat and periphery sharply rounded, with the broadest point about two-thirds of distance from umbilicus to periphery. Umbilical wall short but vertical, passing into flank over a sharp angle of a little more than 90°.
Ornamentation: Lower two-thirds of whorl without costation, but upper third with numerous low rounded ribs arising without any tubercles or projections on the shell. First they are directed slightly forward, but they soon bend to a much more acute angle, and, though they diminish in size towards periphery, they distinctly pass over it with a sharp forward loop. Prominent constrictions, apparently five in a revolution, take their rise from umbilicus, and each of them has a high bolster behind. At first the constrictions slope forward at a moderate angle, and near top of flank they bend farther forward and become parallel with ribs and pass over periphery with a sharp curve forward.
Suture-line of the typical Puzosid form, not dissimilar from that of P. compressa, but more finely divided. In the only specimen that shows a suture-line the external saddle, unfortunately, cannot be seen. First lateral lobe deep and, as usual, wanting in symmetry. First lateral saddle almost equally bifid, and auxiliary lobes and saddles, few in number, form a deep umbilical lobe.
This species is certainly closely related to Puzosia compressa Koss., which comes from the Utatur formation of India, regarded as of Cenomanian
age. It appears to be confined to this formation, for the small specimen figured by Stoliczka is classified by Kossmat as Hauericeras rembda.
Three fragmentary specimens only have been found, and all come from the north side of Bull's Point.