Ticinepomis peyeri, Rieppel, 1980
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publication ID |
https://doi.org/10.1186/s13358-023-00276-4 |
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persistent identifier |
https://treatment.plazi.org/id/3B4E1746-1B12-FFAE-FCE5-FB7AFEE8F9E1 |
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treatment provided by |
Felipe |
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scientific name |
Ticinepomis peyeri |
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Diagnosis (emended)
Ticinepomis species of small size characterised by the following unique combination of characters: premaxilla large; angular with eight round to oval pores plus one pore located between the angular and the splenial; splenial with three large pores for the mandibular sensory canal; splenial with a small symphyseal pore; dentary hook-shaped with the dorsal process more developed than the ventral process; dermal bones ornamented with wavy linear elongated tuberculation to smaller roundish irregular-shaped and coarse tubercles; basal plate of the anterior dorsal fin with a concave ventral margin and a posteroventral spine; basal plate of the posterior dorsal fin with two anterior processes forming an angle of 40°; pelvic bones with narrow processes.
Measurements and meristic
Total body length: 180 mm; d1.f = 9–10; d2.f = 22–23; pect.f = 17; pelv.f = 13; ana.f = 22; cau.f = 15/14–15; n.a = 47; h.a = 19–21
Holotype
PIMUZ T 3925 , a sub-complete specimen of 180 mm long preserved as part and counterpart; Point 902/ Mirigioli , Meride (Canton Ticino, Switzerland); bed unknown, upper Besano Formation , E. curionii Ammonoid Zone , earliest Ladinian (Middle Triassic).
Referred material
PIMUZ T 978, disarticulated and partial specimen showing some bones of the skull including angulars, prearticular, splenial, some bones of the cheek, a lachrymojugal, opercles, supraorbitals, cleithra, bones of the branchial apparatus including a ceratohyal, many small tooth plates, neural arches, and two partial pterygoids; Point 902/Mirigioli, Meride (Canton Ticino, Switzerland); bed unknown, middle/upper Besano Formation, N. secedensis / E. curionii Ammonoid Zone , latest Anisian/ earliest Ladinian (Middle Triassic).
PIMUZ T 1513, specimen showing a complete neurocranium including the parasphenoid, basisphenoid, otic shelf with prootic and basioccipital, some poorly preserved bones of the skull including the parietals, a fragmented opercle, and some scattered bones of the axial skeleton plus one scale of the occipital region; Point 902/Mirigioli, Meride (Canton Ticino, Switzerland); bed 91, middle Besano Formation, N. secedensis Ammonoid Zone , latest Anisian (Middle Triassic).
PIMUZ T 2651, partial specimen of 160 mm length (estimation) preserved on part and counterpart showing the axial skeleton (about 120 mm long) and a partial skull including the postparietal shield (12 mm long) and some other bones; Cave di Besano, Porto Ceresio (Province of Varese, Italy); bed unknown, middle Besano Formation, N. secedensis Ammonoid Zone , latest Anisian (Middle Triassic).
PIMUZ T 2653, disarticulated and partial specimen preserved on part and counterpart; Miniera Val Porina, Meride (Canton Ticino, Switzerland); bed 113, middle Besano Formation, N. secedensis Ammonoid Zone , latest Anisian (Middle Triassic).
Locality and horizon
Point 902/Mirigioli, Meride (Canton Ticino, Switzerland); middle and upper Besano Formation, Nevadites secedensis and Eoprotrachyceras curionii Ammonoid Zones , latest Anisian-to-earliest Ladinian (Middle Triassic).
Description of Ticinepomis peyeri
Generalities
Ticinepomis peyeri , a marine species, was described from Monte San Giorgio (Canton Ticino, Switzerland) by Rieppel (1980) and scored by Forey (1998) for the first time in a phylogenetic analysis. Cavin et al. (2013) proposed some modifications of the scoring based on a re-examination of the holotype of Ticinepomis peyeri (PIMUZ T 3925) and on specimen PIMUZ A/ I 2985 (herein designated the holotype of Ticinepomis ducanensis ). Te re-examination of the holotype of Ticinepomis peyeri (PIMUZ T 3925) and the study of new specimens referred herein to T. peyeri (PIMUZ T 978, 1513, 2653, 2651) allow a better understanding of some characteristics of this species. It is worth noting that the holotype (PIMUZ T 3925) is difficult to interpret due to the particular separation of the part (PIMUZ T 3925a; Fig. 4 View Fig ) and counterpart (PIMUZ T 3925b; Fig. 5 View Fig ), which passed along a parasagittal plane through the specimen breaking several bones of the skull. Te skull was also strongly compressed laterally during fossilization. Terefore, we analysed the holotype by superimposing the photos of the part and counterpart and then varying the transparency of the photos.
Based on the fusion between the supratemporal and the postparietal (an interpretation rejected by Cavin et al. (2013) and in this work), Rieppel (1980) considered that the holotype of T. peyeri (PIMUZ T 3925) represents a fully grown individual. Cavin et al. (2013) proposed that this specimen may not represent a fully grown individual but nevertheless admitted that it was unlikely to represent a juvenile individual, because the ossification stage of its skeleton is too advanced (i.e., presence of fully ossified basal plates). Tis specimen does not indeed represent a juvenile individual but may represent an almost fully grown individual because of its advanced ossification stage and developed ornamentation of the dermal bones.
Dermal bones of the skull
Te postparietal shield of PIMUZ T 3925 is badly crushed, so that its outlines are not clear ( Figs 4 View Fig , 5 View Fig , 6A View Fig ). A sub-complete specimen (PIMUZ T 2651), preserved as part and counterpart, shows a better preserved postparietal shield in internal view ( Fig. 6C View Fig ). Te postparietal shield is found detached from the parietonasal shield, and the anterior border forming the joint margin is straight without any trace of overlap areas. Terefore, the parietonasal and postparietal shields are free from each other.
Parietonasal shield
Te snout is poorly preserved in PIMUZ T 3925. Only the premaxilla (Pmx) can be distinguished. Te posterior snout bones (sn.b) are so badly crushed that almost nothing can be described, except the presence of a small round pore followed by a small notch for the sensory canal that is on the only well-delimited margin (anteriorly located) of one of the snout bones (PIMUZ T 3925a; Fig. 4 View Fig ). Te premaxilla bears four stout conical teeth
( Fig. 5 View Fig ). It is worth noting that the premaxilla is a longitudinally elongated bone ( Cavin et al., 2013 fig. 3b; Rieppel, 1980, fig. 2). Such an elongated premaxilla is unusual in coelacanths, but there is no visible suture or limit that would indicate that this ossification corresponds to the fusion of a small premaxilla with the rostral ossicles. Nevertheless, we consider that the overall snout is too poorly preserved to identify its structure with certainty. Terefore, we refrain from identifying this large bone as a rostropremaxilla bone, which is present in some coelacanths such as Macropoma lewesiensis (Forey, 1998, fig. 3.19A) for instance.
On PIMUZ T 3925, Rieppel (1980, figs 2, 3) identified a series of poorly preserved bones as the supraorbital series (So), but their preservation precludes further description
( Figs 4 View Fig , 5 View Fig , 6B View Fig ). An isolated but well-preserved supraorbital ( Fig. 6E View Fig ) is present in the specimen PIMUZ T 978. Tis squarish bone, ornamented with coarse roundish tubercles, is perforated by four well-marked round pores. Tus, in T. peyeri , the supraorbital sensory canal opens through many pores in the lateral series similarly to Whiteia woodwardi (Forey, 1998) . Tis situation contrasts with Foreyia where this canal opens in a continuous groove ( Cavin et al., 2017) or with Diplurus newarki where it opens with a few pores along the sutural contact of bones (Schaeffer, 1952).
Rieppel (1980, figs 2, 3) identified on the holotype (PIMUZ T 3925b) and figured in his reconstruction a lateral rostral (L.r). Although he correctly identified the bone, he reconstructed it as being very short, which is an odd situation for a coelacanth. Te anterior part of the bone is strongly crushed, but the counterpart ( Fig. 5 View Fig ) suggests a longer bone than the reconstructed one, with the shape reminiscent of the lateral rostral of most other coelacanths. Te ventral process of the lateral rostral does not appear to be developed at all.
On PIMUZ T 3925b above the anterior dorsal margin of the lachrymojugal, lies a triangular to ovoid bony plate that is interpreted here as a large preorbital (Preo)
( Fig. 5 View Fig ). Te bone appears to be visible in internal aspect, which makes impossible to determine if it is ornamented. Although crushed, the interpreted posterior margin of the bone is curved in such a way that it would thus correspond to the orbital margin. Tere are no openings or visible notches for the posterior openings of the rostral organ on the ventral margin that is crushed. Te reconstruction of the cheek of T. peyeri ( Fig. 7 View Fig ) and the posterodorsal curvature of the lateral rostral agrees with the presence of a preorbital. It is worth noting that Rieppel (1980, fig. 2) tentatively identified the bone interpreted here as the preorbital as the basisphenoid. However, there is no structure (as, e.g., antotic process) on this bone supporting this identification.
On PIMUZ T 3925a, Rieppel (1980, fig. 1) identified under the posterior parietal (his frontal) a bony element as the right metapterygoid. However, this element is reminiscent of a ventral process of the skull roof in comparison with other taxa such as in Macropoma (Forey, 1998, fig. 6.10A). According to its position below the posterior parietal (Pa), it is interpreted here as the descending process of the posterior parietal (v.pr.Pa) ( Figs 4 View Fig , 6B View Fig ). It is worth noting that Cavin et al., (2013, fig. 3a) previously identified a descending process of the posterior parietal, but on the basis of another poorly preserved bony element.
Postparietal shield
On PIMUZ T 3925a, Rieppel (1980, fig. 1) identified a curved bone as the postorbital, because it resembles the left postorbital identified on the counterpart. However, its thin ventral region and its position directly below the right postparietal bone suggest rather that this bone is the descending process of the postparietal (v.pr.Pp)
( Figs 4 View Fig , 6B View Fig ). Tis bony element, tapering ventrally, has a large dorsal portion that represents the point of attachment with the postparietal bone.
Below the right supratemporal (Stt), Cavin et al., (2013, fig. 3b) labelled an element on the counterpart as a possible posterior wing of the prootic. Regarding its position and relationship with the supratemporal (PIMUZ T 3925b), this element, similar to the descending process of the parietal identified above, is better interpreted as the descending process of the supratemporal (v.pr.Stt)
( Figs 5 View Fig , 6A View Fig ).
Based on the reconstruction by Rieppel (1980, fig. 3), Forey (1998) scored the posterior margin of the skull roof as being embayed while Cavin et al. (2013) corrected this feature as straight. In PIMUZ T 3925b, the posterior margin of the postparietals is completely crushed precluding to define its exact outline ( Figs 5 View Fig , 6A View Fig ). Te supratemporal, which is somewhat better preserved, appears to have almost straight posterior and lateral margins. In the specimen PIMUZ T 2651 ( Fig. 6C, D View Fig ), the posterior margin of the postparietals appears to be clearly straight along all its width.
On PIMUZ T 3925b, posterior to the right postparietal is a crushed bony element that may correspond to a small extrascapular (Ext.?) ( Fig. 5 View Fig ). Tis interpretation is reinforced by the presence on the specimen PIMUZ T 2651 of a small and well-preserved extrascapular lying behind the postparietal ( Fig. 6C, D View Fig ). Other extrascapular bones are missing in this specimen, indicating that these bones were likely free from the skull. Although it is currently impossible to assess the exact number of extrascapulars, there were probably more than one extrascapular forming the posterior margin of the skull roof.
Dermal bones of the cheek
In all specimens of Ticinepomis , the bones of the cheek are very difficult to interpret due to the poor preservation of this region of the skull.
On PIMUZ T 3925b, Rieppel (1980, fig. 2) identified a tubular bone as the postorbital (Po) lying directly in contact with a comma-shaped squamosal (Sq). It appears, however, that these bones are not in natural contact with each other but rest one above the other ( Fig. 5 View Fig ) (the squamosal hides the ventral portion of the postorbital). Terefore, the postorbital is in fact longer than in the restoration provided by Rieppel (1980, fig. 3). Te postorbital and the squamosal are two bones reduced to narrow tubes surrounding the sensory canal. Te visible postorbital and squamosal belong to the left side of the skull and are preserved in mesial aspect, thus not allowing to see their ornamentation. However, it should be noted that on the right pterygoid, there are traces of ornamentation composed of coarse tubercles that could belong to the right postorbital. Moreover, on PIMUZ T 2651 is a heavily ornamented tubular bone that may be a postorbital, but this part of the fossil requires more preparation to confirm this identification. Although Rieppel (1980, fig. 3) reconstructed the postorbital spanning the intracranial joint, our reconstruction ( Fig. 7 View Fig ) suggests rather that the postorbital lies well behind the intracranial joint.
No independent jugal is identified and this bone was likely absent.
In PIMUZ T 3925, Rieppel (1980, fig. 1) identified a large bone as the preopercle (Pop) ( Figs 4 View Fig , 5 View Fig ). We agree with his identification. Compared to other bones of the cheek, this undifferentiated preopercle is proportionally large. Our reconstruction ( Fig. 7 View Fig ) indicates that the preopercle is positioned under the squamosal and postorbital rather than posteriorly to them. Although this bone is preserved in mesial view, some broken portions clearly indicate that the bone was ornamented with coarse tubercles.
Based on a poorly preserved imprint in PIMUZ T 3925b, lying anteriorly to the preopercle and the squamosal, Rieppel (1980, fig. 3) reconstructed the lachrymojugal (L.j) as a narrow and strongly ventrally curved tube. Following Rieppel (1980) and Cavin et al. (2013), we agree that the lachrymojugal ( Figs 5 View Fig , 8A View Fig ) is a bone with a peculiar shape having a curved and thicker triangular ventral margin. Tis characteristic is similar, but less developed, than on the lachrymojugal of Foreyia ( Cavin et al., 2017, fig. S6, their lachrymojugal + squamosal). Te interpretative drawing of Rieppel (1980, figs 2, 6) suggests that the anterior portion of the lachrymojugal is expanded or angled, but the poor preservation of this bone in PIMUZ T 3925 does not allow to confirm this assumption. On PIMUZ T 978, there is a better preserved lachrymojugal ( Fig. 8B View Fig ). Te shape of the bone fits perfectly with the poorly preserved lachrymojugal of PIMUZ T 3925b as drawn by Rieppel (1980, fig. 2). Unfortunately, the ventral outline of the bone is crushed and the posterior portion is sunk in the matrix, and is covered by a supraorbital and another bone. Te anterior end of the lachrymojugal forms a small angle, as in Whiteia woodwardi (Forey, 1998, figs 4.14 and 4.15) for instance. Te surface of the lachrymojugal is covered with a wavy elongated ornamentation forming ovoid tubercles, which makes it difficult to see the pores for the sensory canal. In the middle of the bone are some very tiny roundish structures, difficult to observe, that may be pores, but this identification is uncertain. On the anterodorsal margin is a large ovoid pore similar to that observed on the lachrymojugal of Whiteia woodwardi (Forey, 1998, figs 4.14 and 4.15). It is assumed here that the infraorbital sensory canal, at least, opens through a few large pores. A notch is dug in the anterior ventral corner that is interpreted here as the mark for the posterior nasal tube ( Fig. 8B View Fig ). Tis identification fits with the pattern of the infraorbital sensory canal that opens, and then passes, above this notch, as for instance in Macropoma or Latimeria (Forey, 1998) .
LoWer jaW
Te lower jaw of the holotype of T. peyeri ( PIMUZ T 3925 ) is much better preserved in its anterior part than in its posterior part ( Figs 4 View Fig , 5 View Fig and 9A View Fig ). On PIMUZ T 978 , we identified a bone as an isolated retroarticular ( Fig. 9B, C View Fig ). It is rectangular with a rounded posterior margin and bears a long surface that is interpreted as the facet of articulation for the quadrate .
On PIMUZ T 978, the bones of the lower jaw, except the dentary, are well visible ( Fig. 9B, C View Fig ). Te angular (Ang) is a shallow and approximately parallel-sided bone ( Fig. 9B View Fig , sC). Tere is a total of eight pores for the mandibular sensory canal (p.m.s.c) on its ventral margin. Te most posterior and anterior pores are elongated and ovoid, while the six other pores in the middle area are almost round and open as three closely spaced pairs. Tere is no visible oral pit line, but the ornamentation makes difficult to ascertain the absence of this feature.
On PIMUZ T 3925a, the prearticular (Part) is difficult to distinguish because of the mode of preservation. On PIMUZ T 978, two prearticulars are well preserved, one entirely in lateral view and one partially in mesial view ( Fig. 9B, C View Fig ). It is a shallow bone with parallel-sided margins that tapers anteriorly. On the lateral side of this bone runs a long ridge, well marked from the middle to the anterior margin, along the mid-depth of the bone. On the partially preserved prearticular, the surface is densely covered with small conical round teeth. Few teeth are ornamented with very fine and faint striae that are hard to detect.
Te splenial (Spl) appears to be angled downwards anteriorly on PIMUZ T 3925b ( Figs 3C View Fig , 5 View Fig , 9A View Fig ), a peculiar feature that is even more pronounced on the splenial of PIMUZ T 978 ( Fig. 9B, C View Fig ). In this specimen, the splenial is well preserved and displays additional characteristics not visible on PIMUZ T 3925. Te bone is smooth and unornamented like the dentary but unlike the angular. Te mandibular sensory canal opens laterally in the mid-depth of the splenial with three large and elongated rectangular pores. Tere is one large and elongated pore that opens between the splenial and the angular. On the anterior margin of the splenial is a large notch, which, when in contact with its antimere, forms a large symphysial pore. A symphysial pore on the splenial is also present in Foreyia and Whiteia woodwardi (drawn but not labelled or described in Forey, 1998, fig. 5.9A), and possibly in Luopingcoelacanthus (not described but suggested by the illustrations provided by Wen et al., 2013, figs 1, 2A). Te shape of the splenial and the arrangement of the pores of T. peyeri are reminiscent of the pattern in Foreyia , except that in the latter, there are only two pores in the mid-height of the bone ( Cavin et al., 2017, fig. S6) and not three pores like in T. peyeri .
Te dentary (Den) of T. peyeri bears a strong and well-developed hook-shaped process ( Figs 5 View Fig , 9A View Fig ). Te presence of a dentary pore in T. peyeri remains unknown because of the poor preservation in available specimens.
Rieppel (1980) reported on PIMUZ T 3925a the presence of two coronoids (the ‘precoronoids’ of Rieppel), just above the location of the dentary based on PIMUZ T 3925b. At least five conical teeth are borne on the best-preserved coronoid (Cor) ( Figs 4 View Fig , 10A View Fig ). On PIMUZ T 3925b is a small bony plate with three visible conical teeth, which is regarded as a tooth plate (t.p) ( Fig. 5 View Fig ), because it is smaller and has a different shape from the coronoids. On PIMUZ T 978, there are some similar small bony structures with teeth that may also be interpreted as coronoids and tooth plates ( Fig. 10B View Fig ).
Te bone on PIMUZ T 3925b labelled by Rieppel (1980, fig. 2) as a coronoid is more precisely the principal coronoid (p.Cor) preserved as a very fragmented bone on a poor imprint ( Figs 4 View Fig , 5 View Fig ). Although poorly preserved, this bone is not sutured to the angular. It is worth noting that Forey (1998) scored in his phylogenetic analysis the principal coronoid in a reverse way, i.e., as sutured to the angular.
Te gular plates (Gu) are poorly preserved but clearly discernible on PIMUZ T 3925 ( Figs 4 View Fig , 5 View Fig ). On PIMUZ T 978, two well-preserved smooth, without any trace of tubercular ornamentation gular plates are preserved
( Fig. 9B, C View Fig ). Both bear small well-marked gular pit line (gu.p.l) in their middle portion. On the gular plate of PIMUZ T 3925b ( Fig. 5 View Fig ) is the imprint of a ridge running parallel to the lateral edge along the anteroposterior axis, which is regarded as the ridge observed in Megalocoelacanthus and Latimeria (Dutel et al., 2012) for instance, corresponding to the insertion point of the anterior and posterior ramus of the intermandibular muscle.
Neurocranium, palatoquadrate, parasphenoid, and gill arches
On PIMUZ T 1513, bones of the neurocranium are well preserved in natural position under the parietals ( Fig. 11 View Fig ) and most of the following characters are described from this specimen. Te neurocranium appears to be derived among coelacanths by having the orbitosphenoid and basisphenoid regions separate from one another, the temporal region not lined with bone and the otico-occipital separated to prootic/opisthotic. On the basisphenoid (Bsph) ( Fig. 11 View Fig ), the paired processus connectens (pr.con) are positioned in such a way that they do not meet the parasphenoid. No basipterygoid processes are present on the basisphenoid. Te antotic process (ant. pt) is unfortunately broken, but its emplacement can be detected.
Te basioccipital (Boc) is ossified as an independent bone ( Fig. 11 View Fig ), which is a feature also found in Ticinepomis ducanensis sp. nov. ( Cavin et al., 2013, fig. 5). Te prootic (Pro) is attached to the basioccipital by a wavy complex suture ( Fig. 11 View Fig ). Te prootic develops a small posterior wing (p.w.Pro), as it can be observed in Macropoma (Forey, 1998, fig. 6.10B) for instance. Te otico-occipital portion of the neurocranium of Ticinepomis then appears to be ossified into distinct units, which is a characteristic found in derived coelacanths (Forey, 1998).
Te parasphenoid (Par) is preserved in ventral view
( Fig. 11 View Fig ). Te toothed portion is well developed and extends on the two-thirds of the overall ventral surface of the parasphenoid. On this surface are borne conical and pointed teeth with fine striae ( Fig. 10D View Fig ). Along the external portion of the mid-length of the parasphenoid toothed patch, the teeth are large and decrease in size posteriorly until they are reduced to tiny bulges on the most posterior part. Te teeth are small and of equal size across the median portion of the bone. Te parasphenoid is not pierced by the foramen for the buccohypophysial canal, meaning that this canal is closed. Anteriorly, the dorsal margin of the parasphenoid bears a well-developed ascending lamina, which lies in contact with a separate lateral ethmoid.
In PIMUZ T 3925, Rieppel (1980, fig. 1) already identified bones of the palatoquadrate, but the quadrate is unknown and the shape of the metapterygoid and pterygoid are hard to detect because of the peculiar preservation of the specimen. Only two roughly triangular autopalatine (Aup) and a bony element with strong conical teeth interpreted as the dermopalatine (Dpl) (palatinum of Rieppel, 1980) can be clearly discerned
( Figs 4–5 View Fig View Fig ). In PIMUZ T 978, all the bones of the palatoquadrate ( Fig. 12 View Fig ), including a metapterygoid (Mpt), a pterygoid (Pt), a quadrate (Q), an ectopterygoid (Ecpt), and a possible dermopalatine (could also be a coronoid), are well preserved. All these bones, except the possible dermopalatine, are preserved close to but detached from each other. Te metapterygoid is a robust and almost square-shaped bone, while in PIMUZ T 3925a and in PIMUZ T 2653, the metapterygoid appears to be narrower. Te mesial surface of the pterygoid of PIMUZ T 978 is densely covered with small-striated conical teeth
( Fig. 10C View Fig ). Unfortunately, the ventral margin of the pterygoid is not well preserved and we cannot assess the condition of the ventral swelling. Te ectopterygoid is elongated and bears small conical teeth that are apparently smooth. Te isolated bone of PIMUZ T 978, identified either as a dermopalatine or a coronoid ( Fig. 10B View Fig ), bears strong conical teeth, which seem to be smooth with no detectable striae, unlike the teeth observed on the pterygoid and parasphenoid.
Tree basibranchial tooth plates (Bb.t.p) are visible in PIMUZ T 3925 (Rieppel, 1980, fig. 1) and include two anterior and one posterior basibranchial tooth plates
( Fig. 4 View Fig ). Te two anterior basibranchial tooth plates are paired and not fused together. Unfortunately, the posterior portion of the basibranchial tooth plate’s series is covered by bones of the jaw, making it impossible to determine if there are two or more pairs of basibranchial tooth plates. Te teeth of the basibranchial tooth plates cannot be seen, because the bones are preserved in ventral aspect.
In PIMUZ T 978, there is a well-preserved ceratohyal (Ch) ( Fig. 9B View Fig ). Tis long and curved bone has an expanded distal extremity and a thinner proximal extremity. At its mid-length is a well-developed ventral process, reminiscent in shape to the ventral process of the ceratohyal of Luopingcoelacanthus (Wen et al., 2013, fig. 3E).
AXial skeleton
In his description of PIMUZ T 3925, Rieppel (1980) mentioned 51 neural arches, including 33 and 18 neural arches in the abdominal and the caudal regions, respectively. However, regarding the interpretative drawing of Rieppel (1980, fig. 4), only 47 arches are clearly drawn, including 32 neural arches, 21 haemal arches, and 15 radials. In the upper lobe of the caudal fin, we counted directly on the specimen 15 radials supporting each a fin ray, plus two anterior supplementary radials supporting no fin ray. In the lower lobe, we count 14 to 15 radials supporting each a fin ray plus two anterior supplementary radials supporting no fin ray. PIMUZ T 2651 displays the axial skeleton including neural and haemal arches in natural position, except for the five anterior first neural arches slightly detached and away from the rest of the column. In this specimen, we count a total of 47 neural arches and about 19 haemal arches. Unfortunately, the caudal fin rays, radials, and haemal arches are difficult to count, because they are preserved compressed against one another. In the upper lobe, we counted 15 rays plus one posterior most ray that seems to belong to the supplementary lobe, not being supported by a radial. Anteriorly, there is at least one radial, possibly two, that supports no ray. Tus, 15 rays and 15–17 radials in the upper lobe of the caudal fin are recognised. Tis number of radials and fin rays is consistent with PIMUZ T 3925. Te three anterior most rays in both lobes bear small and sharp denticles. T. peyeri has 31 or 32 neural arches which are not incorporated in the caudal fin and 15 or 16 neural arches in the caudal fin for a total of 47 neural arches. Posterior neural and haemal arches are not abutting one another as already stated by Forey (1998). Te caudal fin is composed of 15 and 14–15 radials each supporting one fin ray plus two additional non-supporting radials in the upper and lower lobes, respectively. Terefore, there is a one-to-one relationship between the radials and the fin rays in the tail, as already stated by previous workers.
Paired fins
In his emended diagnosis of Ticinepomis, Forey (1998) stated that the fin rays are slightly expanded, an assumption rejected here. Indeed, all fins of T. peyeri present slender rays and are clearly not expanded as in Libys polypterus (Ferrante et al., 2022; Lambers, 1992, fig. 1 and pl. 1) for instance.
| PIMUZ |
Palaontologisches Institut und Museum der Universitat Zurich |
| T |
Tavera, Department of Geology and Geophysics |
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