Magnoliaephyllum alternans, Heer, 1926

Greguš, Josef & Kvaček, Jiří, 2015, Revision Of Cenomanian Flora From The Maletín Sandstone, Acta Musei Nationalis Pragae Series B 71 (3 - 4), pp. 315-364 : 328-330

Magnoliaephyllum alternans

(HEER in CAPELLINI et HEER) SEWARD

Pl. 11, Fig. 1–5; Pl. 12, Fig. 1–7; Pl. 13, Fig. 1–5; Pl. 14, Fig. 1–2

1866 Magnolia alternans HEER in CAPELLINI et HEER, p. 20, pl. 3, fig. 2–4.

1866 Magnolia capellinii HEER in CAPELLINI et HEER, p. 21, pl. 3, fig. 5–6.

1869 Ficus krausiana HEER , p. 15, pl. 5, fig. 3–6.

1869 Ficus mohliana HEER , p. 15, pl. 5, fig. 2.

1869 Daphnophyllum fraasii HEER , p. 17, pl. 6, fig. 1–2.

1869 Daphnophyllum crassinervium HEER , p. 18, pl. 7, fig. 2, pl. 11, fig. 5.

1869 Magnolia speciosa HEER , p. 20, pl. 7, fig. 1, pl. 9, fig. 2, pl. 10, fig. 1–2, pl. 11, fig. 1.

1869 Magnolia amplifolia HEER , p. 21, pl. 8, fig. 1–2, pl. 9, fig. 1.

1869 Juglans crassipes HEER , p. 23, pl. 6, fig. 3.

1874 Magnolia capellinii HEER in CAPELLINI et HEER; Heer, p. 115, pl. 33, fig. 1–4.

1874 Magnolia alternans HEER in CAPELLINI et HEER; Heer, p. 116, pl. 33, fig. 5–6, pl. 34, fig. 4.

1913 Magnolia alternans HEER in CAPELLINI et HEER; Fritel, p. 289, text-fig. 3–8.

1927 Magnoliaephyllum alternans (HEER in CAPELLINI et HEER) SEWARD, p. 120, text-fig. 25.

1999 Dicotylophyllum cf. alternans (HEER in CAPELLINI et HEER) KNOBLOCH, p. 41, pl. 13, fig. 8.

L e c t o t y p e: Pl. 11, Fig. 1, designated here; Capellini and Heer 1866, p. 20, pl. 3, fig. 3.

It will be necessary to choose a lectotype from Oswald Heer’s collection, which were not available to the present study.

T y p e l o c a l i t y: Tekamah , Nebraska, USA .

T y p e h o r i z o n: Dakota Formation, Cenomanian, Upper Cretaceous ( Knowlton 1898, Upchurch and Dilcher 1990).

M a t e r i a l s t u d i e d: GBA_2, 3a, 6, 7, 8, 9, 11, 12, 17, 18, 19, 22, 23, 26, 27a–c, 28, 29, 33, 41, 42, 44, 45, 48, 49, 50, 51, 53, 54, 55, 56, 57, 60a, b, 61, 62, 63, 64, 65, 68, 69, 71, 72, 73, 75, 80, 81, 82, 83, 84, 85, 86, 88, 89, 90, 91, 92, 93, 94, 97, 99, 100, 101, 102, 103, 104, 113, 116, 121, 130, 131, 135, 137, 144, 153, 154, 155, 156; GPIT/PL_623, 626, 628, 635, 637, 647, 655, 663, 664, 665, 666, 668, 669, 670, 677, 679, 683, 688, 689, 693, 694, 695, 696, 697, 698, 699, 700, 701, 703, 704, 705, 706, 707, 708, 709, 710, 711, 712, 713, 714, 715, 719, 734, 735, 746, 747, 748, 752, 753, 754, 756; MMT (M)/G_323, 325, 326, 352, 353, 354, 357, 358, 365, 367, 375, 381, 382, 384, 385, 388, 390, 393, 394, 400, 404, 405, 406, 425, 434, 435, 436, 437, 442, 446, 449, 452, 463, 465, 475, 476, 477, 480, 482, 490; MMT (Z)/ G_317, 327, 355, 359, 374, 383, 386, 387, 389, 451; MZM/118_3, 7, 8, 9, 11, 13, 15, 17, 20, 21, 23, 24, 27, 29, 35, 36, 38, 39, 43, 45, 47, 54, 55, 56, 57, 59, 61, 64, 65; NHMW_8, 10, 13, 14, 15, 18, 19, 20, 21, 22, 24, 26; SMNS/650_1, 2, 5, 8, 9, 10, 11, 13, 14, 15; UGV_2, 3, 4, 7, 9, 10, 11, 12, 13, 14, 17, 18, 21; VMO_30.104, 6296, 8088, 8089, 8092, 8093.

O c c u r r e n c e i n C z e c h R e p u b l i c: Maletín, Kunštát, Rudka, Březina, Vyšehořovice, Slivenec (Peruc-Korycany Formation).

E m e n d e d d i a g n o s i s. Leaves entire-margined medium to large, ovate and longitudinally to widely elliptic. Apex acute to attenuate, base cuneate. Venation pinnate, brochidodromous to eucamptodromous. Occasional shorter and straight intersecondary veins present. Venation of higher order subtle, often not apparent.

D e s c r i p t i o n. The suggested lectotype (Pl. 11, Fig. 1) described by Heer (Heer in Capellini and Heer 1866) from Dakota Cretaceous Formation (Tekamah locality, Nebraska). The lectotype is an elliptical leaf with petiole, without preserved uppermost part of apex. Entire-margined leaf shows a cuneate base. Fragment of apical part tapers into an attenuate apex. Secondary veins brochidodromous, departing from relatively robust midvein at 40° angle. Short and subtle intersecondary veins occur between secondary veins, they arise approximately in the middle of the leaf lamina. The specimens described by Heer (1869) as D. crassinervium (GPIT/PL_719, Pl. 11, Fig. 5; SMNS/650_9, Pl. 11, Fig. 4), D. ellipticum (GPIT/PL_734, Pl. 11, Fig. 3) and Daphnophyllum fraasii (SMNS/650_8, Pl. 11, Fig. 2) are entire-margined, elliptical to wide elliptical leaf impressions with cuneate base. They are widest at one-third or one-half of their length. Acute apex is preserved only in specimen no. GPIT/PL_734. All leaf impressions have fragmentarily preserved petioles. Relatively small leaf impression no. GPIT/PL_734 is only 118 mm long and 58 mm wide (L/W=2). The second almost preserved leaf impression no. SMNS/650_8 is 182 mm long and 65 mm wide (L/W=2.8). Secondary veins run from the relatively robust midvein at 35–40° angles. Leaf impression no. GPIT/PL_734 shows in the right side of the leaf lamina an apparent dichotomous branching of secondary veins (Pl. 11, Fig. 3). Similar branching is also apparent to the right upper side of specimen no. GPIT/PL_719 (Pl. 11, Fig. 5). This atypical forking is not apparent in the rest of the specimens. Specimens no. GPIT/PL_719 and GPIT/PL_734 show an apparent suprabasal vein, which runs almost parallel with the cuneate base. On the left half of leaf impression no. GPIT/PL_734 veins of third order run out from the first secondary vein, which are connected to the suprabasal vein. Occasional intersecondary veins are present.

Leaf impression no. SMNS/650_5 (Pl. 12, Fig. 1), described by Heer (1869) as Ficus mohliana is a 217 mm long and 52 mm wide, entire-margined impression of longitudinally elliptic leaf, with narrow cuneate base and attenuate apex. This leaf impression is the widest in its middle part. Length to width ratio is 4.2. A well pronounced midvein is remarkably narrowed in the direction of the apical part. Poorly preserved secondary veins run out from the primary vein at an angle of 40°. Other specimens described by Heer (1869) as Ficus krausiana are two impressions of entire-margined elliptical leaves. These impressions are widest in their lower half. The first impression (SMNS/ 650_2, Pl. 12, Fig. 2) has an acute apex. A small part of the missing base suggests a cuneate shape. Estimated length of the impression is 200 mm. Width is 53 mm; length to width ratio is 3.7. The primary midvein is relatively wide. Poorly preserved secondary veins depart from midvein at an angle of 35–40°. Near the margin of the leaf lamina, some veins show brochidodromous loops. Another, better preserved specimen (SMNS/650_1, Pl. 12, Fig. 3) is an approximately 175 mm long and 46 mm wide leaf impression, with a cuneate base and oblong attenuate apex. Length to width ratio is 3.8. Small parts of the base and apex are not preserved. Brochidodromous secondary veins depart the midvein at a 40° angle. Leaf impression (GPIT/PL_746, Pl. 12, Fig. 4), described by Heer (1869) as Juglans crassipes is entire-margined, elliptic with a cuneate base and not preserved apical part. It is widest in its middle part. Estimated length of the leaf impression is 165 mm, and width is 63 mm; length to width ratio is 2.6. The leaf shows a cuneate base with relatively long (50 mm) and wide petiole, and missing apex. Secondary venation is brochidodromous. Intersecondary veins are present.

The leaf impressions described by Heer (1869) as Magnolia speciosa is entire-margined, widely elliptical with cuneate bases and attenuate apices ( GPIT / PL _735, Pl. 12, Fig. 7; GPIT / PL _747, Pl. 12, Fig. 6; GPIT / PL _752, Pl. 13, Fig. 1; GPIT / PL _754, Pl. 13, Fig. 2; GPIT / PL _756, Pl. 12, Fig. 5). The largest leaf impression no. GPIT / PL _756 is 250 mm long and 92 mm wide ( L / W =2.7). Other leaf impressions are approximately 20 mm long and 8 mm wide ( L / W =2.5). Primary venation pinnate; secondary venation of brochidodromous type departing from relatively wide midvein at a 45–50° angle. All impressions have at least partially preserved petiole. Specimen no. GPIT / PL _754 has a well pronounced long petiole (41 mm) .

Leaf impressions of magnolioid-type described by Heer (1869) as Magnolia amplifolia (GPIT/PL_753, Pl. 13, Fig. 4; SMNS/650_13, Pl. 13, Fig. 3) are entire-margined, widely elliptic to obovate with cuneate base. The leaves are widest in the first third of their length. Apical parts are not preserved; judging by the convergent margins of leaf lamina, they were probably attenuate. Specimen (GPIT/PL_753) could be originally up to 220 mm long and 106 mm wide (L/W=2.1). Secondary venation of brochidodromous to eucamptodromous type with veins depart a relatively wide midvein at a 40° angle. Some veins do not reach the margin, and end at approximately 2/3 of length of other veins. Intersecondary veins are sometimes present. The newly discovered counterpart (GPIT/PL_666, Pl. 13, Fig. 5) to Heer's (1869) original (GPIT/PL_753, Pl. 13, Fig. 4) shows a clearly cuneate base and roughly sinuate margin. Other material from Starý Maletín consists of approximately 200 specimens of complete and nearly complete leaf impressions, and 25 fragments. All specimens are entire-margined, elliptic and widely elliptic to ovate. The best preserved specimens are 115–280 mm long and 42–150 mm wide (average: L= 202 mm, W= 84 mm). Length to width ratio is 1.5–3.7 (average: 2.5). Venation is in most cases well preserved. Venation is pinnate, with secondary veins showing brochidodromous loops. Intersecondary veins are present. A few specimens have venation poorly preserved or missing. However, a number of specimens also show third order venation, which is percurrent (GBA_18, Pl. 14, Fig. 1a, b; GBA_29, Pl. 14, Fig. 2a, b). Most leaf impressions have preserved at least fragments of the petiole. Specimens no. GPIT/PL_746 (Pl. 12, Fig. 4) and no. GPIT/PL_754 (Pl. 13, Fig. 2) show very long petiole.

D i s c u s s i o n. Heer ( Capellini and Heer 1866, Heer 1869) described eight new species of magnolioid-type leaf impressions, which he classified under the genera Daphnophyllum , Ficus , Juglans and Magnolia . Leaf impressions described by Heer are entire-margined, with similar elliptical shape, with cuneate base and attenuate apex. During his life, the leaf impressions were freshly collected, so the venation was more apparent. Despite this, he described only secondary venation. Today, higher order venation is seen on only a few specimens. Venation of these leaf impressions has very similar or identical architecture. Because Heer had only a few specimens, he classified the species according to their variable secondary characters, such as a moderately elongated apical part. In this case, we studied and compared almost 200 specimens, and concluded that among these leaf impressions, there is great variability, with smooth transitions in shape, size (including length to width ratio) and venation. This is confirmed by Fritel (1913), who described and illustrated the modern species Magnolia grandiflora LINNAEUS , which has clear variability in elliptical leaf, with transition to ovate leaf, but also obovate leaf. With regards to great variability, Fritel (1913) synonymised the species Ficus krausiana HEER , Daphnophyllum crassinervium HEER , D. ellipticum HEER , D. fraasii HEER , Juglans crassipes HEER , Magnolia amplifolia HEER , M. capellinii HEER , M. speciosa HEER to the species Magnolia alternans . Knobloch (1999) is also inclined to regard these as the same species. Knobloch classifies these impressions to the artificial genus Dicotylophyllum SAPORTA. Due to the character of these impressions from Maletín, it is not possible to determine systematic position in recent botanical classification.

Leaf impressions from the Nebraska Cretaceous described by Heer ( Capellini and Heer 1866) as Magnolia alternans are, with their shape and simple type of venation, morphologically identical to the Cenomanian species Magnolia amplifolia , which Heer (1869) described from the Bohemian Cretaceous Basin.

Fossil leaves of the magnolioid-type, with preserved epidermal anatomy were described by Upchurch and Dilcher (1990) from the SE Nebraska Cretaceous (Rose Creek, USA). For this fossil material, a new genus Pandemophyllum UPCHURCH et DILCHER was established, with the type species Pandemophyllum kvacekii UPCHURCH et DILCHER .

Upchurch and Dilcher (1990) remark in their publication that there is a possible relationship between the new genus Pandemophyllum and Heer's (1869) genera. As Z. Kvaček (1983) mentions, Magnolia amplifolia , Daphnophyllum crassinervium and D. ellipticum (in this paper classified in genus Magnoliaephyllum ) are very similar in their anatomical features to Myrtophyllum geinitzii HEER , which in this paper we describe as Myrtoidea geinitzii (HEER) J. KVAČEK et GREGUŠ comb. nov. Myrtoidea geinitzii is defined by an intramarginal vein, which is missing in leaves of M. alternans .

High-quality and complete leaf impressions of M. alternans are very typical of the Maletín plant assemblage, and quite numerous compared to other species. This situation is, beside frequent occurrence of this leaf type in the Maletín sandstone, caused by human factor: during intensive quarrying of Maletín sandstone, it was easy for quarry workers to collect fossil impressions, and naturally, they only selected the best pieces.

As Pek and Mikuláš (1997) mention, leaves of M. alternans are curved, waved and have cross grooves and ridges, and even structures similar to recent insect burrows, although this observation is not new – Heer (1869) observed these same structures (“Insektengallen”) over a century earlier.